 So, I think according to our plan today, we start discussion on the astronomy in media of India. And in media of India, I mean to say actually, Siddhanti astronomy was continuing, but main thing that because of outside innovation started coming again and again and the rulers were also coming from outside. It is not like previously the shocks coming, wounds coming, but they are getting absorbed here, but this time the rulers were coming from outside. So, lot of activities were interrupted and many well south of Bhinjar, but at the same time the new influence came and some new types of astronomical activity started and some of those things we will discuss. So, today what we will discuss is that interaction with the O-station G's astronomy which we call and then important contribution by Shwai Jai Singh and it will be interesting because though he did not do any fundamentally new work, but his observatories you all see and they stand still as more or less as tourist attraction I must say. So, when he played some role in astronomy, now the northern part of India, the astronomy continued to be pursued, but under the influence of waste station astronomers and sleep rulers and as a natural consequence to that G's astronomy took roots in Indian soil. What is G's astronomy? Now in West Asia one of the main task of the astronomers was to prepare astronomical tables called G's. Now G's is a table, astronomical table and they needed it very badly because they follow also strictly lunar calendar as you all know and this kind of astronomy which is primarily based upon G's that is table they are called commonly G's astronomy. So, there are three types of G's, one type of G's is G's is G's is a Shidi and G's is a Hishabi and G's is a Tasheel. From the word I think those who are known who do well they can find out, one is with observation and one table is based primarily on calculation used some other some other persons observation and the last one I am not very sure what is that. G's is a Tasheel is simplified tables for easy application to specific tasks like studying the motion of the moon alone not the whole of astronomy and G's is a Hishabi or Hishab what is familiar to you. These tables presented with the calculated data taking care of various types of corrections and effects in the observed data but it does not involve observation directly and G's is a Rasadi not this is a Rasadi these are tables of raw data obtained from the direct observation. So, these three types of G's were there and there is nothing fundamental in you but the name was this because of that historical connection. The first the no major development in Siddhantic Astronomy took place during this period much much later of course you will find that for the end of 19th century the Samanta Chandrasekhar also developed some new types of instruments and improved the accuracy substantially but otherwise there was no difference. The first major impact on West Asian astronomy was made by the early Siddhantic astronomy as I mentioned yesterday and it was done through the translation of Sanskrit texts into Arabic. According to A.C. Rizvi he quote the foundation of Islamic astronomy started during the reign of Abbasi, Khalifa, Al Mansu in 753 A.D. a copy of Brahmagupta Siddhanta or Brahmagupta Siddhanta it is the same thing was brought to Baghdad from Sindh in 770 A.D. and was presented to Al Mansu. A retention title Sindhan Hind it was translated and name was called Sindh Hind was prepared by Yakub Ibn Tarik and Ibrahim Fajari. Later Aryah Hattiam was also translated by Abul Hussein Awaji into Arabic and the title was Arjavad. Another popular classic was Khanda Khardaka you know it was a corona text of Brahmagupta's Brahmagupta Siddhanta. Now you know corona text were simplified algorithms for direct calculation without going to theory etc. and this Khanda Khardaka was a very popular corona text and that was also translated as Arkand by Yakub Ibn Tarik and these three classics remained as the basis of astronomy in West Asia. According to Syed Suleyman Nadavi though Ptolemy was translated as al-Majisti that is why you call it al-Majist if you now buy a copy of in our library we have it Ptolemy's it is called al-Majist but actually originate is al-Majisti for long and the Arabic astronomers from Baghdad to Spain clung to the Siddhanta genre primarily. Now as Al Birumi was a very important person in the history of West Asian astronomy he lived during the 973 to 1048 A.D. and was the most important person in West Asia astronomical science. He visited India in 1070 A.D. and spent 14 years studying various branches of Indian science and mathematics. Being a scholar in Persian, Arabic and Sanskrit he wrote 27 books on different aspects of India. I have a couple of them. Now he held many Indian astronomers in very high esteem with Brahmagupta at the top. Like Professor C. A. Nalino of Roe mentions quote, the Muhammadan owe the first scientific elements of astronomy to India. These Indian works had many imitators in the Muhammadan world up to the end of the first half of the 5th century of Izra that is 11th century A.D. Till that time it is the transition of Siddhantic texts were taking. Of course what really the progress was made was through observation. They contributed substantially through continued observation which were more accurate and as I will tell you some of the good observatories were developed there much much before Jai Singh developed the observatories in India. Now this astronomy in medieval India, the first this was prepared during 753 to 754 by Al-Fazari based upon Brahmagupta Siddhanta as I mentioned. Important work was done by Mohamad Bin San Ali Kawazmi who fused three contemporary systems like Greek, Al-Majest, Persian, Zizi, Sahariya and Indian Siddhanta and subsequently the most noted astronomer in the Islamic world was Uluk Beg. Spelling is wrong, I think it is not Ulik, it is Uluk. Uluk Beg was the most famous and competent astronomer from Samarkand in the 15th century A.D. This Zizi Uluk Beg had lasting influence on astronomy in medieval India and formal introduction of Zizi astronomy in India was by Il-Tut-Mis, you have heard about Il-Tut-Mis in history in the 13th century A.D. He was the first to bring Zizi astronomy in India and got it introduced in the system here. During the Delhi-Sultanate period, Amir Khushu was also a very competent astronomer and he composed his well-known poem on 28 nakshatras as Al-Manazil. When the first Zizi was compiled in India, the court astronomer of Hiroshath Glock, 14th century A.D. Mahendra Shuri compiled Jantra Raja and Hiroshath Bramani of Deccan was himself interested in astronomy. Actually he thought of constructing the first observatory in Balaghat in the 15th century A.D. but I think it did not come up because there is no trace of it. Taimur's innovation really destabilized whole of North India and all scientific work came to a halt. Only after the beginning of Mughal dynasty, work on astronomy and astrology started with face enthusiasm. Mumbai himself was a very good astronomer and nurtured the growth of the subject. Actually it is told that he failed from this year by viewing Venus and he also had his astrolabe and he used to decide timing, etc., everything based on his astrological calculation. So he failed while observing Venus and going backwards and that fall was quite serious for him as you might have read in history books. Ultimately he died. So Humayun was of course not only an astronomer but he helped development of astronomy. And major calendrical reforms also took place during Akbar's time. Akbar did lot of things and that was another thing, the reform of the calendars. And he also started a new era, not the Hijira but another one and there were around 86 Jesus in his time. And for the first time in India after the Mughal dynasty that means what is in the going time that means the grandson of Alangir, five major observatories were constructed by Jaisen which I will discuss. Discussing more Jesus and this is not much important because they do not have any fundamentally new contribution to astronomy so far as India is concerned. So I think what I will do now that I will discuss the instruments which were used for naked eye astronomy and you have seen the accuracy. See Jaisen's observatories except one wrist had an accuracy of 3 minutes of arc and the biggest one which you see in that is what is the Parliament's study that is that has accuracy of 1 minute of arc. Now this is one instrument which was very popular amongst the vegetarian astronomers even Hellenistic astronomer and it came to India along with the Muslim rulers, astrolabes and they are very popular among the Greek also. But however in Indian ancient astronomy the astrolabes are not mentioned and it is quite obvious that they are not here. So these devices were for astronomical and astrological computations you know. So it consists of number of disks with various markings somewhat like a surplus light rule you know and many computations could be done, calculations could be done and of course the astrolabes just like any sky map you have to see it like this. Don't try to see it like that it will be totally confusing. So just as you see sky it has to be done like that and this is the basic picture what astrolabes represented and the principle of astrolabes was based on stereographic projection of the celestial circles on a plane. So what you do the outer circle here that represents the Tropic of Capricorn. In Tropic of Capricorn means Makar Kranti you know not Karkat Kranti but Makar Kranti. Then what you do you divide by two perpendicular lines north, south, east ways. Now you can easily see you have to view it putting it overhead. Then only directions will match. Then with this O as center and I think what happened this epsilon was I think our 23.5 degrees. The point A was the first point you have to get and this point A was represented by the intersection of the outer circle and the radial line which is drawn and this angle is the inclination of Earth's axis with the plane 23.5 degrees. So after getting this point you join E point and A point where it intersected this S O line at x and you draw a circle with O x as diameter radius and this is the equator. Next what you do after you get the equator then point B and C point B and point C are found out because this circle intersected at this point the line O A at B and you draw a line where this circle intersects line E W that is C join this line then this intersects the line S O at D and then draw a circle with O as center and O D as the radius and this represents the topic of cancer. And when you draw a circle like this this is the then you have to draw another circle with this as diameter this point and this point this is the circle and this circle represents the ecliptic and this is the topic of cancer and this is topic of capricorn and this is the I think equator was this one. So now I think this is just the stereographic projection keeping your eye at the south pole. So this is a three dimensional view I will not go into detail explanation it will take time and I also I have never seen any astrolabe in mind but I see you can see if you go to Jaipur and visit that only thing you know that Jai Singh had a big astrolabe but his grandson or son as you remember he used it as a target practice and Daniel did very much you know for his gun you know he was practicing no interest in astronomy. So this figure above shows the stereographic projection of the celestial sphere on the equatorial plane keeping the eye on the south celestial pole and the main purpose was as you can realize is representing the three dimensional sky on a flat plane. So these instruments look like this you have seen in history book or history of science book it consisted of number of distance. So the main container was called rate A and then team pans these are number of thin number of them for different latitudes each latitude had one with lot of markings et cetera and they used to be kept in the frame and they could they are joined by a pin and they could be moved and with all different adjustments it could make lot of astrological astronomical calculations and computations. The details you can go to internet you can see the website detailed explanation is there how it is done. Actually I will also request some of you if you are interested in this institute things are done why don't you make a good astrolabe here for IIT Kanpur and keep it somewhere I will be very happy if I find it next time when I come make one you can get all the details in the internet of its making and they look like that and I think you know with the help of with your extra knowledge and modern foundation in science maybe you can develop a better one. Another kind of device which used to be used which was also in ancient Indian astronomers history they are called armillary sphere. Now the astrolabe was a two dimensional projection of the sky on a flat plane whereas armillary spheres were actually three dimensional system representing the sky, earth et cetera. So this is one typical armillary sphere I am saying you see even Arya Bhatt describes Arya Bhatt starts saying quote the sphere or Gola Jantra they used to call it Gola Jantra which is made of wood perfectly spherical uniformly dense all round but light in weight should be made to rotate keeping pace with time slowly as earth rotates with the help of mercury oil and water by the application of one's own intelligence. So you can think of you can apply your intelligence and make a device which will rotate with the earth. Now here you see that it was having I have used different colors which is of course not the case. So this is the Gola, Gola means circles represent the earth things and this is the Gola that is the sky. So here you can see that the circles and this is the prime vertical meridian then I think equator is this one. Where is the equator? This one, this is the equator and this is the ecliptic. There are two circles that is 23.5 degree angle is one meridian and this is the axis about which earth rotates. And this is the six o'clock circle there used to be one and this is the south celestial pole, this is the north celestial pole. This is Nadi, this is Zenith. Gola means? Gola means this is the celestial sphere and this is the horizon circle. So these were used even in India and I think if you look into history of science books, scientists sitting in Astroma you will find an ordinary sphere there. So nowadays of course it is often used because you can have much better things with the help of computer. You have seen that how you can have the planetarium software. There are far, far superior software which of course you can buy but the software I have shown you and I am leaving it here. It is free student version and you can get it easily. Those who want I think, request professor Amit Dutta I think you can copy it from here. I am not sure. Someone has to come to my office and take it. No, I am saying that one can copy a software from after it is installed I am not sure about these things. A computer science will be able to tell. This is hard. Because it is already installed here. Can you take it? I think that will be better than that. Now I think I will discuss some. So when we are in the work, he said that there is astro. But I could write, I could write. He said that there was this figure. I could write. He said that there was what I showed in the previous lecture. No, no, no. His main things were actually a quadrant. You will find that in those days, I will show that more or less these are the instruments which I am going to explain now. Even from ancient times, they used to use these as the common instruments. It will look to you not like instruments like children's toys kind of thing but it could give that kind of accuracy you can see. So don't have any disrespect towards these things, you know. One thing is most important instrument is a shanku. It is a stick put at right angles to the horizontal and its shadow of that is to be used for different purposes. For example, if you are asked to find out the true north and true east, how are you going to do it? You can easily do it. Go to the ground and find out the true north and true east and true south. So it is simple what they will do, that they will draw a circle and at sunrise, so after sunrise, the sunrise is here, sometime you will find there is a shadow, some length. After few hours, you again take the shadow and do it in a manner so that the length of the shadow is same. So how it is done, you draw a circle and whenever the shadow touches that circle, you take two such shadows and then bisect it. It will show in the northern hemisphere, it will show the northern direction and perpendicularity of this place. So that is the simplest way. On a sunny day of course, not on a cloudy day, you can find out the true north, true south, etc. And that was primarily what they have done. And so who had other kinds of things and it is not only for finding out the true east, true west and true north, but also as a time indicator for the whole day. That has been, that is why sundial. Sundials are also basically a similar instrument and you will see that our jai-sings, main things are basically similar principle. There is one jasti-jantar, that is a stick. It is only to find out the altitude kind of thing, the angle with the horizon with the particular thing. It could be sun, it could be other thing. But in case of sun, it will be done in such a manner that there will be no shadow at that instant. And this is the angle which is the altitude of the sun. There is another kind of, there are two sticks. One is long, another is perpendicular short. So I want to find out the angle between one direction and a star for example. So I put the main stick towards the direction with which I want to measure the angle of the star and then this way I move this along this till this point and this point aligns with the star. And then this angle will be measured, you can measure. That is, that was used for finding out the, this is shalaka-jantar, this is jasti-jantar. So they used for finding out the angle between a star and a particular direction. It could be another star also. Then we had star, jasti-jantar, again another type of jasti. And this is sakata-jantar. So there is one string and there are two sticks hinged here. So that is also there, you know, how to measure the angle between two heavenly objects like this. A very simple thing, you know, child's play, not even TA-101 level thing. So these are called chakrasantra. So this chakrasantra, they are used by Arya Bhatt also. So this chakrasantra was a hook and diametrically opposite, there are two holes. So you put it on a horizontal plane, you rotate the plane of the hook about a vertical axis till it matches with the plane in which the sun is contained. Then rotate the hook without changing the plane so that the sun may pass through the two holes and falls here. So then using the dimensions etc., you can find out its azimuth and altitude, all those things you could measure. Another one is of course that from the two ends there are two hanging strings and it is held in hand and from the length of the strings you can find out the angle. Just variation of the same principle, of course. Chakrasantra, again some more chakrasantras. So here the vertical is indicated by a pendulum kind of thing. That is what our plum or plumbers do, you know, use. And then from the center there is a pin and there is a plum and there is a hole and you adjust the hole in such a way that you can see. And this angle, we will call the zenith distance or the angle it makes with the vertical and so on. And here this pin is here and this is a disc which is hanging vertically and then this shadow wherever it falls, so it will automatically, this is a perpendicular line to this and which has to be vertical because it is hanging. So this used to be called as the altitude, obviously. And this is dhanur jantra. This is like a semicircle or dhanush. So you put one diameter on the horizontal flow and rotate it so that the, it matches the plane of this dhanush, matches with the plane of the sun and there is a pin here. You shift the pin along this till the shadow of the pin falls at the center. So therefore this, I think, gives various things like this is the best circle. So you can get the angle, altitude of this and also this is the sunrise point is just like that. So this is called dhanur jantra. These are other types of dhanur jantra. Here it is a semicircle and there is a plum and this is one of the radius perpendicular to this. Now you align this side diameter with the star, with your eye and measuring this plum location here, you can see that what is the angle and that is the altitude of this star. Obviously because if this is a plum, it has to be vertical. Similarly here also you will find, you know one thing you have noticed perhaps in some cases I am showing sun, in some cases it is star. Wherever you are using shadow kind of thing, it is because this is the sun and where direct viewing you can see it is a star. Say of course you cannot look at sun like this, you know in no time you will become blind. You know that when we are asked not to look at solar eclipse, it is not any religious stigma, it is dangerous. The reason is very simple, that when the sun is full, you cannot look at it. It is so bright, you cannot your leaves will automatically close. But when there is only a crescent of the sun, you can very easily look at it. It is so nice to look at. But the image which is formed on retina of that crescent of the sun, its intensity is the same. So it damages the retina. This is proven fact and that is why it is said that not to look at. Because you can easily look it is a very thin line or diamond ring all kinds of things are told, you know. But the image which is formed it is as dangerous as the real full sun. So therefore whenever there is some kind of thing, it is always a shadow. There is a pin here so the shadow is cast here and you can say this is the altitude. These are all variations of the same thing. Now this is Bhagana or Narivalaya Jantra. As you will see even Jai Singh did this. Narivalaya Jantra, now this plane, this plane is actually parallel to equatorial plane, you know. And this is a pin perpendicular to this at center. And here the shadow, you know on the equinoctial day shadow will not fall or it will fall on both sides. And in the Tarayan period you will find when the sun is on the north then shadow will fall here. When the sun is towards the south then shadow will fall on the other side. And this way you can find out all dimensions measuring its angle and all those things. You will see more detailed Narivalaya Jantra constructed by Jai Singh. This is called Kartari Jantra. These are all variations. Kartari Jantra is again two semicircular discs at right angles. One is east-west, one is north-south and if you point it to the north pole, you know and this will be the east-west measurements and the markings are there, shadow etc. This is also a type of Kartari Jantra but this Kapala Jantra is interesting. It is nothing but a huge bold hemispherical bold and at the top there are two cross this are two thin wares at right angles, at two diameters and so this point is the center of the surface here and inside surface of this hemispherical surface they are given all kinds of markings. Then when the shadow of this crosswear falls on that looking at the location of this point you can get many things like time, altitude everything you can get to know. So these are called Kapala Jantra. Now you see I come to Sai Jai Singh and a little bit of his life which is very interesting. Now Jai Singh the Raja Swai Jai Singh of Angar he was born in 1688 and lived till 1743. Now we have told that his position is very unique but also I think there are some unfortunate things you know. So whatever the Euro-Sentic Western scholars might find a chance of observation in ancient Indian astronomy but there are ample evidence as you have told Shupa. Now what happened that when Jai Singh inherited the throne of Ambe after his father Vishnu Singh died in 1780 at the age of only 27 at Kabul. He was fighting along with the Mughal in the decline and to control the Marathas engaged in constant guerrilla warfare in the Deccan Jai Singh was sent by Aurangzeb to the south. Jai Singh was only 14 years old at that time. There when he was in the south he met a young mathematician and astronomer Jagannath and that friendship was a lasting friendship with everything. So what happened as such the foundation for a lasting friendship with him was laid and after Aurangzeb's death in 1707 when Jai Singh was still in the south the political situation in Delhi became very uncertain. The whole thing was being controlled by actually a group of people they are called council of Amir Swaram Rahim and then Aurangzeb's great grandson Muhammad Shah as the emperor Jai Singh was on a relatively good terms Aurangzeb of course was very old you know and served him in various capacities though even with Jai Singh's control was over in his native area Amir that measured no more than 7500 square kilometer by 1730 his authority extended to a much larger territory from Delhi to Normala in fact during that period Jai Singh enjoyed more power and respect than the emperor according to a French Jesuit traveler. Now observators of Jai Singh which is our interest so whether Jai Singh had more interest in ruling a kingdom or perjuring astronomy is not known but he knew Arabic and Persian and as well as Sanskrit and was quite familiar with Islamic Siddhantas. He had a number of astronomers in his court the most important among them was of course Jagannath and who translated Al-Pussi Arabic version of Talimi's Al-Majest into Sanskrit under the title Sambharata Siddhanta his other court astronomer was Ray Kebaljum from Gujarat and he wrote a dozen books etc and Jai Singh also compiled a jeez called Ii Muhammad Sahi in the name of his friend Muhammad Sahi but actually it was nothing but these days it will be called plagiarism what he did was Ulugbeks jeez actually now interesting thing is that he was at a time when Copernican theory etc was there was known but he was unaware he thought that he checked all the tables he was finding the results were not accurate enough and he thought that this non-accuracy is due to inaccuracy in observation he never suspected that our model of this system of the universe was wrong so he thought his main concern was Ticrobial like Ticrobial to improve the accuracy taking instrument with small wood or metal pieces they are subject to many distortions he thought he will make observatories using machine with stone concrete or something like that and that is how and he wanted to make them big and that is why actually there are quite a few observatories he set up and primary aim was improving the observational accuracy and these are known as Jantar Mantra which originally called Jantar Mantra Sanskrit term in Delhi it was constructed during 1720 to 24 and there are 7 major instruments in Jaipur the construction was from 1728 to 1734 and there are 14 major instruments Varanasi 1724 and there are 5 instruments with Jaim there are 1730 there are 7 instruments and Mathura 1734 there are 5 instruments so these 5 Jantar Mantras were there in Varanasi I think the Jantar Mantra of the observatory was erected on the terrace of Manmandira that was the name of a palace constructed by Jai Singh's ancestor Raja Man Singh and that is why today astronomical observatories are called Manmandira in India or Hindi isn't it and that originated from that the Varanasi observatory was erected on the roof of Manmandira was the name of the palace so we call astronomical observatories also as Manmandira now you see that though his objective was to improve accuracy by having bigger system made of stone and machinery etc so the accuracy of Ulupeg's observatory erected 3 centuries before Jai Singh had the same accuracy Jai Singh's observatory instruments as I mentioned had plus minus 3 minutes of arc accuracy and he is the largest one the Samarata Jantra which I will explain and discuss it had plus minus 1 minute of arc accuracy which is better than Tycopa here and that is also considered the limit of naked eye astronomy instrument where you can sextant eye so there actually which one was 1 minute of arc accuracy accuracy that means suppose you are measuring the angle between 2 objects or you are measuring the altitude or measuring the the azimuth whatever it is any angle because astronomical observation is nothing but angle measurement there is nothing like distance it is only angle so the actual value and the accuracy with which you could measure it that is the use so that is why here we say it is like this but in real life it is not that simple they are all genius to make the accuracy so I am told that in reading they used to take very accurately and there is to be large number of assistants also it is not impossible to handle all those things by one person so Tycopa also had a large number of assistants same thing with Jai Singh they had large number of assistants no I understand that one gear kind of thing like your micrometer principle was discovered in towards the end of 19th century so I think this is very unfortunate thing you know and why it happened why Jai Singh did not it was there, couple of things were there the heliocentric model concept by Galileo you can see Galileo and Jai Singh they are contemporaneous isn't it Galileo was born in 1565 or so and died at 1642 and Jai Singh's date I told was 1688 actually he was after Galileo almost at the time of Newton so I think why by that time gravitation law etc all are known the reason is there he at that time interaction with the west started and lot of jesuit priests used to come from Europe and Jai Singh and they used to bring I think all knowledge of west I think European astronomy and Jai Singh took lot of interest in that and he used to depend quite a lot on them so once he sent a team to Spain I think or Portugal I don't remember he used to bring more information more modern information now all the jesuit priests were very much against heliocentric model you know that that's why George and Bruno was burnt alive Galileo was put in jail so they did their best to prevent Jai Singh in getting active in heliocentric astronomy so that's why Jai Singh depended on them so much on the modern development but they almost isolated him from the development but it is told that Jai Singh had a telescope I'll read it later and he had something which is not known but I have read in a history of science book published by your India National Science Academy this I also didn't know I'll tell you here I could tell it later but it is better to tell and Jai Singh knew certain things and perhaps did some experiment with telescope that need to be done so SMR Ansari he is a scholar who deals with the history of astronomy I have read his paper and he reference to Jai Singh's knowledge based on telescopic astronomy are found on the following topics the electricity of the lunar and solar orbits the existence of four Jovian satellites obloid shape of planet Saturn because at that time the ring was not clearly visible you know Galileo saw it first he first thought that planet has two years and you know in those days the scientist used to do very funny things he observed something and then he thought whether to publish it or not he thought that if it is something stupid he should not publish it because there was so much of acrimony and other things because of the paradigm shift was taking place so what he did he sent a secret message which could be deciphered as the discovery of Saturn these two bulges and sent it to some other scientist hoping that when later it is discovered and it is found to be true he will claim his priority but after sometime he was horrified to see that those bulges are gone so he was so scared that then again after quite a long time what happened actually he shattered the ring planes at that instant the plane of the ring was coinciding with our line of vision so we could not see the bulges the rings are very thin you know so if you are looking along the edge of the ring you will not see them that is precisely happened at that location Saturn's ring plane was matching with the line of vision but again after sometime those bulges reappeared and then he told that I have observed these please and also it was a new discovery a planet with ears and later he found that there are two circles but he didn't know that they are rings so therefore the obloid shape of planet Saturn was the kind of knowledge they had and phase of planet Venus and Mercury so why Jai Singh did not pay too much effort and attention to telescopic observation there is another theory because with telescope at that time was a qualitative measurement till the cross wire was invented and attached to telescope it was not a measuring instrument it was just like a binocular kind of thing once the cross wire thing was developed it started giving numerical quantitative factors so telescope was not very useful as a his objective was to have more accurate observation that means he has to get measurements with telescope measurements were not possible at that time secondly the heliocentric model of Gokernikas the results were no better than the deocentric model of Ptolemy so there was no impetus on Jai Singh to really go for heliocentric model but I don't know where answer he found this but he says that these are there in the writings where Jai Singh he had a telescope and he had these observations I will now discuss something about Jai Singh's instruments developed by Jai Singh this is the most important and most prominent instrument you know samrat jantra and you have seen that it is nothing but a equinoctial sundial kind of thing equinoctial sundial something like that naribala jantra that a plane which is parallel to the plane of the equator that is sometimes they are called equatorial sundial that is the same thing and then there is a shanku and the shadow falls on that so here you see what was the samrat jantra's basic principle that this is thin it is like a set square you know a thin slab vertical and this angle is equal to the latitude of the place in the location and it is oriented towards in the north south direction exactly and then perpendicular to this plane there was a circular path q east to q west and from here then what happened and this was a solid thing so when sun comes the shadow of this edge will fall at some location here and that will tell you the time accurately have you gone to Delhi to see jantra mantra you have seen the markings on marble there so if the sun is there this will cast a shadow on the quadrant in the morning the shadow will be on the western quadrant and in the afternoon it will be on the eastern quadrant obviously and that will give you the time of the day just like a sunrise again there is a rod here which you can move along this and there are markings so this rod you are moving till the shadow of the rod falls at this point and the marking here will tell you the altitude of the sun so primarily the time and altitude of the sun these are the two things you can get very accurately with an accuracy of 1 minute of art size is big I am telling you its size is height of that end height is 22.6 meter so it is 6 to the building I believe the accuracy comes obviously so this is a 6 to the high building height 22 meters 22.6 meters the daily that daily it looks like this and as I mentioned that the declaration north and declaration south to find out right ascension and declaration I told you in the equatorial system so you have to shift this rod along this and when the shadow of the rod falls here this angle is the declaration and that is marked here so one thing is very clear the marking or engraving has to be non-linear it is not linear you can see that so 45 to 60 is so much 30 to 45 is so much and 0 to 30 is only this much so marking if you go to Delhi now the actual shape of samrat jantra is something like this isn't it and let me see the photograph I have one this is the one I am talking about this jantra that is a 6 to the building and actually this is a smaller version these are the quadrants eastern quadrant western quadrant and the steps are there because somebody has to go up and down yes this angle if it is inaccurate obviously everything will be inaccurate but it is obvious because you see it is equatorial system that means this this you know these are parallel to equatorial plane okay and it has to be perpendicular to that so anything which is perpendicular to that it is nothing but the shanku like yeah it is nothing but equinoctial sandaya just that very large size so if it has to be perpendicular to the equatorial plane that means it has to point towards north pole isn't it and this angle has to be latitude measuring latitude is a relatively simple problem that is a relatively simple problem yes so I think they had for that tables etc they all had that so that means depending on the season you know what is the declination everything will change of course and actual shape is like this you know I have gone one long back you know these days only I pass by that parchment street somebody is giving dharma and all kind it is used for that purpose I believe these days and if we take there I think it is not allowed to take food inside or is it earlier it is to your picnic spot I remember in 62 when I was there so these are the gyacin's observatory for naked eye astronomy there are various jantras other jantras as I mentioned kapala and gyaprakasha jantra the kapala jantra this is a huge bowl and I explain this and these are the two wares or ropes this acts as a cross wear and inside their markings are there where the shadow falls and from the shadow the marking gives that what is the reading and somebody will go inside and will see the size of this kapala jantra in Delhi I think the diameter of the this jantra in Delhi in Jaipur Delhi is 8.3 meter about 25-30 feet that is the diameter next is digamsa jantra digamsa jantra is used primarily for measuring the azimuth angle of the heavenly objects and it consisted of two concentric circular walls with a central pillar I have shown that here this is a central pillar those two circular walls and there are two ropes one is east-west direction one is north-south direction and another rope with a hanging weight here so you can when you want to view something of a star so then you have to move this along this till this and these are in the same plane and this angle is given as the azimuth angle so the size of the jantra here in Delhi it was built only in Jaipur Varanasi and Ujjain Delhi it is not there and the wall height was this was a three-storey building this height and this height was just slightly less than one storey so this was actually a three-storey building so it will look like a huge circular enclave and this is the cross section how it is this is height h this is h by 2 this is the sectional view but in not all cases it is h by 2 in Ujjain it is different as I can see but these are all pretty big machinery works as Jaipur he wanted higher accuracy but the accuracy unfortunately was not more than that of Ulugbeg which was constructed 300 years back these are two important jantras, Nadi Varanasi jantra these are again nothing but equinoctial sandayals two one on the north face another is the south face these are parallel to equatorial plain and this is pointing towards north pole this is pointing towards south pole looks like this and again a dial is there so it is for measuring the time and identifying the equinoctial points equinoctial day what will happen that it will be exactly parallel and both will cast shadow so that day and other days only one side will be having the shadow on the next was Ramajantra so and this is Nadi Varanasi jantra in Jaipur the plate diameter was 3.6 meters that means how many feet 12 feet kind of thing 11-12 feet and the separation was about 16-17 feet and Ramjantra is Ramjantra name was given perhaps after his grandfather Ram Singh many people think that way and the instrument was in the form of a cylindrical structure with open top and a pole with the same height as the surrounding cylindrical walls and the floor and the inner cylindrical surfaces was engraved with scales indicating azimuth and altitude very simple to follow so there is a pillar here and these are all vertical line scales and here they are radial lines so when there is some the shadow falls here and from that you can easily find out the azimuth looking at where it is falling vertical when it is going here so you can measure at a time measuring the shadow and its location and the reading you can get both azimuth and altitude these are the main things these angles you know astronomy is nothing about measuring these angles so Ramjantra is size let me see if it gives yes in Ramjantra was constructed only in Delhi and Jaipur wall height and the radius for Delhi Ramjantra about like a two-storey building it is 7.5 meters the accuracy for both of this the order of 6 periods of arc all the marking so 6 minutes of arc accuracy you had in this Ramjantra then the most famous and most attractive Jantra is there which is generally photographed and this is really astronomical it was never used very much and neither it gives any better result that is called Mr. Jantra small thing the diameter of the sun is about 20 minutes or so no 30 points some 30 minutes so 6 minutes means one side of the sun only one side they were very careful about when they touch one side comes then only they do so then so the Mr. Jantra in this photograph many places it is a very attractive structure and most photograph structure so far as this Jantar Mantra is concerned but it is not really very useful it was a combination of various Jantras you know it combined Samrad Jantra, these Jantra and quite a few others and observationally it was not very important neither was it very used only it was a kind of nice looking sophisticated thing and I think your also pretty big I do not remember the sizes are not given here I think the scale is here so this is 20 feet as I have given the scale so you can see this whole thing is about 100 feet kind of thing it is a pretty big massive thing this is one of the this is one of the this is another symmetric thing this is another quadrant and this is a myth chakra I do not know all kinds of changes now I think you know Jai Singh's aim was to rejuvenate Indian astronomy rather than really pursuing the truth and unfortunately he could not achieve a clunk to the geocentric model to bring the wisdom from Europe he chose a wrong country Portugal for sending his envoy not Italy thus hardly any modern idea was brought back to him he also spent money and effort on building perpetual machines that took lot of time and effort it was said that an amount of equivalent to US dollar 25,000 was spent by him on experiments in that direction constructing perpetual machines even though Jai Singh was born after Newton's Principia was published Jai Singh's astronomy remain archaic in character he had the telescope but it did not occur to him to use it as an astronomical instrument the reason I told you it started becoming an instrument only after the technology of crosswear was developed in so he died in 1743 and his second son Mahjoh Singh demonstrated some interest in astronomy in fact it was he who built the Mishra Jantra of them that of course many may not know the Mishra Jantra was constructed by his son and that's why it didn't have much astronomical importance and he had the opportunity to become a pioneer with his resources his interest in astronomy he wonderful assistant like Jagannath but I think he chose the wrong people and the result was this the last one in the whole history of siddhantic astronomy was Samanta Chandrasekhar of Oisa he was born in 1835 and died in 1904 so you can see it is a very recent thing he was even in the 20th century and the last siddhantic taste was written by him this is called siddhantra dhaktana it had 24 chapters and had 2500 slokas out of which 2284 was his own compositions and he was definitely very talented person and in seclusion he grew up so he was unaware of the happenings you can see by that time in India itself his telescopic astronomy was quite prevalent but he clung to the same old siddhantic astronomy and naked eye astronomy so the in spite of that fact of course his siddhant dhaktana he noticed the inaccuracies and he tried to improve the accuracy and you can see the improvement which is very apparent here these are nothing but the inclination of the planetary orbits according to the various siddhantas the planetary orbits you know various planetary orbits are inclined to the ecliptic plane as I mentioned so that angle is very important to make good estimate and good correction so you can see the five planets you know here and along with moon they are inclination to the ecliptic plane in Surya siddhanta it is moon 4.3 degrees in siddhanta 0.8 is 4.3 siddhanta dharpana 5.09 and actual modern value is 5.0833 so you can see the substantial improvement which is the correct value and siddhanta dharpana samanta chandrasukha is this whereas the old values were quite inaccurate so when you go to mercury which is very difficult to observe mercury is so near sun extremely difficult to observe Surya siddhanta gave a value of 5.55 siddhanta ceremony gave 6.55 your siddhanta dharpana gives 7.02 and here you can see it is 5 degrees 0.9 I must say you should keep that in mind up to minute of arc, second of arc you can ignore so 5.09 means 5 degrees 0.9 minutes here it goes up to second modern value of course so 7 degrees 0.2 minutes siddhanta dharpana was so accurate here it is 7 minutes and 0018 18 seconds so I think it is very clear that he made tremendous improvement in accuracy with his instruments also simple nekera instruments which he designed he constructed he did not have any instrument like jai siddhanta no all the hand held so and you can see the improvement in accuracy so his his life history you can find in the book I am not reading it so his instrument his own observational instruments is developed of course they will resemble some of the instruments in siddhanta takes but one of his instrument called monajantra it is very interesting you know it looked like I am unable to resist the temptation how it looked so these are serrations with different angles you know this was his own invention because no such instrument is found in any siddhant he called all the texts and with this monajantra was his own invention it was a multipurpose instrument that could measure you see latitude, altitude genus distance, suns declination, angular separation and the suns position in the zodiac and this instrument in the form of a T as I showed and crossed up was engraved with 24 slots with progressively increasing inclination and it could do so much with such accuracy he also designed chapa jantra for measuring time and gola jantra and that was also similar to kapa jantra like that so his siddhanta darpana is still in use in orissa because all things puja, sacrifices, etc in jagannath temple they are all guided by samant chandrasikas calculations and not only there but even in the society of orissa most of the households panchang prepared following the siddhanta darpana even till today so however the fact remains that he was very much in the telescopic era but he devoted his whole life actually he was not known then one I think it is sometimes just for the sake of the story you should know some of the chandrasikas were represented more as an astrologer people thought he was an outstanding astrologer he was a gifted astronomer and he was born in 1835 as I have shown in khandapada 100 kilometer west of Bhuvaneshwar it was a small state surrounded by hills and jungles samanta was born in a royal family when his uncle ruled this small state his early education was primarily in Sanskrit and Sanskrit based literature at the age of 10 his uncle introduced him to the basics of astronomy and samanta himself learnt the siddhantika when he was 15 he wanted to check the astronomical predictions of siddhantas through his own observations with the instruments made by him to his utter dismay samanta found the predictions to fail in predicting correctly the positions of the planets and stars repeated checks finally convinced him that established texts like shurya siddhanta siddhanta siramuni needed further correction then he took it as his life's ambition to incorporate all the necessary corrections in siddhanto astronomy amazingly he designed his own instruments for naked eye astronomical observations yielding results with much better accuracy starting at the age of 15 samanta chandrasikas began his astronomical observations and theoretical analysis for the next eight years reaching the age of 23 samanta started systemizing the huge data collected by him and at the age of 26 he started writing the text compiled by him the last siddhantic text siddhantadapati he wrote the book in oriascript on palm leaves because of his isolation from modern educated world the text remained confined to a corner of his house for 30 years on his chance meeting with Prof. Mahesh Chandra Nairatna principal of Sanskrit college Calcutta during one of his Orissa tours Prof. Nairatna was greatly impressed by his talent and it was Prof. Nairatna who introduced samanta to Prof. Yogesh Chandra Roy of Patak college present there Avinso college who played a key role in getting the siddhantadapati published in Debnagari script from Calcutta in the year 1898 only after this the outside world came to know about Samanta Chandra Siddhartha and his valuable work so that is the end of siddhantic astronomy in India and I think tomorrow the last what I will do I will give some interesting very interesting and in the history of astronomy they have remained as a fascinating stories with tragic results sometimes they are not tragic stories you will see and the beginning of telescopic astronomy but major part of tomorrow I will also discuss the whatever the recent research tells about the antiquity of Indian astronomy and also the originality how much of it is original and some discussion on the controversies about the originality of nakshatra system different scholars view and discuss that I will not discuss much about the development of radio telescope etc in India that is a modern period and that is not the objective of this because they are all current things going on so I think if there are few questions we can discuss that this Jyobesh Chandra Rai is he the author of this book on Bengali book on Jyotishi do you know probably he is who have done lot of work in the 19th century was Kalinath Mukherjee was one and 20th century I have told pieces and books and others but in the previous century Kalinath Mukherjee was actually you know inspired by Herschel's grandson he was a civil servant in the district of Nodhya where and he taught Herschel's grandson Kalichar Mukherjee and he was a lawyer and he has astronomy at his own so how is the story of Siddhantic astronomy I think it is very interesting you have you have already found out you know we are discussing about the Katapaya system so he has worked hard and he has found out yes that slope gives the value of pi I think it is that Shankaracharya Puri Shankaracharya who has also written that Vedic he has given that so was there interaction between mathematicians and astronomers actually same thing mathematics a lot of development trigonometry and other things on astronomy and astronomy also a lot to mathematics and since Indian mathematics was most developed so it is obvious that our things will be superior to others so one more question so did their school come to them was some system built especially for R. A. Bhatta they had disciples obviously they had disciples the whole subject I think there are thousands of astronomers who have worked we have presented only small miniscule fraction of that even I have not been able to discuss who are the very famous astronomers you have shown the picture no one has used magnet as a what what no one no one has used magnet for what magnet does not give you accurate reaction at all magnetic is not magnetic north also varies from place to place from time to time you are interested in the celestial pole to north not the magnetic north north is different from the true north it was known to Kepler actually at that time his name was Gilbert who wrote the first book that was at the time of Kepler and from that only Kepler got the idea of gravitation the idea of gravitation first came from Kepler and he told that every object attracts every object and they move towards the common point the amount of movement depends on their relative bulk so it is Newton is not the originator of gravitation theory this is part of his three books Kepler's idea of gravitation is not part of his book is it written in the book Kepler's idea of gravitation you can even get it it is all very clear only thing problem was he thought that gravitational force the force was proportional to velocity everybody the concept of accelerating and linking with force was first by Huygens that was the real breakthrough he showed that force is proportional to acceleration and the constant of proportionality was N that was Newton the omega square r was known to Huygens he developed it and using that and Kepler's third law they found out that the gravitational force is inversely proportional to square of distance by Halley and Hooke that was also known much before Newton okay any other questions okay thank you