 I think it is worth spending some time in telling them generally what engineering is about, in particular what mechanical engineering is about and in that the place of thermal engineering and in that thermal dynamics. A typical thing which I do is the following. I say that look we are human beings here and I draw it at a very low level just to emphasize that at the other end nature is supreme. We have nature which provides us with lots of resources. Many of those resources or all the resources are natural. For example, everyone agrees that sun is the source of almost all energy that we have today. But it is available to us in very indirect ways. You know the wind is solar energy because of its effects on the earth's atmosphere. So is the tidal energy, wave energy, water at a height because of monsoon, all direct indirect effects of solar energy. Firewood from jungles and forests which grow and we cut them unnecessarily, so that is also a solar energy. Historically, forests and fossils created millions of years ago give us our fossil today. So you tell them that sun, then fuels, then wind, what not. These are all natural resources and what we want is to have a good life, comfortable life. And the thing we do to bring these two together is generally known as engineering. That is the way I teach them. Whatever we do to use our nature for our own good is engineering. We use all our ingenuity for, may not be a perfect definition but satisfies the students and because we are not learning engineering philosophy in general, let us leave it at that. Then I say what is mechanical engineering about. You start very simply, you tell them that mechanical engineering, now I am saying making is about machines. Now what is the job of these machines, what kinds of machines, all sorts of machines. But finally remember that machines have to do something which provide us a good life. So this computer which I am using is a machine. The wristwatch which I am using allowing me to keep track of my time is a machine. This lamp, this projector, fan, air condition, all these are machines. But how do machines work, they have to be provided some energy. So there must be some machines which make use of these natural resources of various kinds and convert those resources into useful energy. And why do we need that energy? We need that energy in part to drive these machines. This is a machine but it requires an energy, that is a machine it requires energy. So there must be some other machine which makes use of a natural resource, converts it into energy because a block of wood, we know its energy, a small pile of uranium, we know its energy. But we must have some contraption, some machine to convert it into useful energy. And everybody knows that a shaft turning is useful energy, I can use it for sharpening a pencil, I can use it for driving my car, I can use it for driving a generator to create electricity, all those things that is one way of machine. How do the machines come about? There are machines which produce machines. So machines which manufacture machines, machines which convert natural resources into energy and I tell them that this is not complete, there will be machines which do many other things. But this is the main theme of machines and mechanical engineering is all things about such machines. And remember that final aim is to provide a good life to us humans, provide us air conditioning, provide us transportation, provide us peace of mind, everything. I find that something like this is good for them to understand what mechanical engineering is about. And you tell them that this is not a textbook definition of mechanical engineering. In fact I have not found the proper textbook definition of mechanical engineering which is good for explaining to students. But if you tell them that mechanical engineering is about machines, machines that convert natural resources into energy, machines that drive machines through this energy, machines that produce machines of various kinds and the end product of all this would be to provide a good life for us directly or indirectly. And so long as a machine of certain kind is involved, mechanical engineering is involved. After this introduction to mechanical engineering, the next thing I say is look, conversion of natural resources into useful energy and making use of this useful energy to drive some machines is what thermal engineering is about. So I say that this part conversion into useful energy which is later used to drive machines is what thermal engineering is about. Mechanical engineering has to done with machines which handle energy, either convert them from one part to another or use it and use that to drive some machine or make use of natural resources to provide energy in any useful form. And then I say that look when it comes to this behavior of this energy and transformation of it into one form or the other, the basic science and engineering at the bottom of all this is thermodynamics. Then I say that look whenever there is an energy transfer involved, either transfer, conversion, thermodynamics is involved. This is not the basic definition of thermodynamics but I say this is where thermodynamics will poke its fingers in. And I also tell them that and it is necessary to tell them because at that stage they have a feeling that mechanical engineering has nothing to do with electrical engineering, there is nothing to do with chemical engineering. These are watertight partitions, that is not true. You tell them when you talk of thermodynamics that look thermodynamics is such a basic science that it has been of interest to physicists, chemists from the science side even biologists. On the other hand it is of immense use to engineers, so almost all types of engineers look at it. Mechanical definitely, chemical also, metallurgy material science also, electrical also, electronics also. The limits to the behavior of machines, compactness of computers, compactness and efficiency of our mobile phones, tablets, laptops are today thermal limits, those are the major limits. And the moment there are thermal limits, something about energy transfer, efficient energy conversion, thermodynamics will be involved. So the thermodynamics has something to do with science and engineering of energy, handling energy conversion, energy transfer. That is the basic idea of thermodynamics. And now it is important to emphasize that let us say that we agree what engineering is. But then partitioning of engineering and before that the partitioning of science into groups or subjects like physics, chemistry, biology is to some extent arbitrary. When you come to physical chemistry, you know you have physical chemist and you have chemical physicists and they keep on fighting about where the boundary lies. Actually, there is no boundary. The boundary is an artificially dotted line created by us human beings. So the separation of various topics in science into physics, chemistry, biology etc. is to some extent arbitrary. The partitioning of engineering into its branches like mechanical, electrical, chemical, civil is much more arbitrary. You cannot say if you take mechanical and electrical engineering, you cannot say where mechanical engineering ends and where electrical engineering begins. If you have a college of engineering with a reasonable number of branch, I am sure between any two branches even apart from first year there will be a few common courses. You cannot have a good course in mechanical engineering and a good course in say chemical engineering without saying not a single common course. It may not be two courses, may be two different numbers, two different papers but if you look at the syllabus there will be lot many topics in common. And that is because the boundaries between the various disciplines of engineering are very, very arbitrary and they are not fixed boundaries. They keep on changing. Whatever what is in mechanical engineering today may be in some other part of engineering. For example, thermodynamics was part of mechanical engineering since ages. Chemical engineers and metallurgical engineers picked it up later. But heat transfer as a formal science developed in chemical engineering first and then was picked up significantly by mechanical engineering. All these changes occurred typically between 1950s and 1960s and those of you who are oldish will realize that till about mid-60s in many colleges there was a three-year engineering program. Later on it became four-year engineering program. The fourth year was added because it was realized that there is a set of subjects called engineering sciences which are on the borderline of sciences and engineering. Mechanics, thermodynamics, fluid mechanics, control theory, mainly from the mechanical engineering point of view there are network theory, electric fields and circuits for electrical engineers and I am sure there are other subjects of this kind. So these are all of interest to various branches of engineering and thermodynamics for some reason tends to encroach over a large number of these branches. So that is the type of discussion one has to have with students so that the, you know you put a framework around what engineering is, what mechanical engineering is, in mechanical engineering what we call thermal engineering or the energy related engineering. And thermodynamics is at the heart of that but also say that look thermodynamics is not the unique domain of mechanical engineers and we should not fight about it, it is a common science and it is of use not only to engineers but to scientists, various branches of science, various branches of engineering and then you should say that for thermodynamics we will build up on our knowledge from physics, chemistry and we will use some mathematical tools, these three ideas we will be using, ideas from physics, chemistry and mathematics to develop our abilities in thermodynamics. And then we say that look do not stop here, question immediately comes in is where is thermodynamics used in mechanical engineering and at that time or maybe even earlier when you talk of engineering and thermal engineering you should emphasize the various aspects of thermal energy of mechanical engineering. We have put in our earlier discussion machines at the heart of mechanical engineering, so mechanical engineering is everything about machines, we must know how to design them, we must know how to manufacture or make them, we must know how to use them and since many of these machines will be handling energy we must know enough about energy. So at that time we say that look mechanical engineering has various aspects, one of the aspects is thermal energy which is handling of energy and machines that handle energy. Then the machines are made of materials, we must know how strong and weak that material is, so that we design an engine which does the job for a reasonably long time without failing, that aspect is taken care of by subjects like solid mechanics, theory of machines, machine design, so called design engineering part of mechanical engineering. And then you say that after designing it somebody has to use some tools like piling, turning, casting to assemble the whole thing, make and assemble the whole machine and make it run for us, that is our manufacturing engineering or production engineering, these are the three main parts of mechanical engineering, of course you have control systems and industrial engineering which are not unique to mechanical engineering but which are needed to put all these three parts together. So you say that in thermal engineering after thermodynamics or along with it you will have to learn subjects like fluid mechanics, why? Because much of the energy which is transferred is transferred through fluids, we compress fluids, we cool them, we pressurize them, we depressurize them, we heat them, we boil them, we condense them, so a large amount of fluid is handled and then just the way solid mechanics is important for solids, fluid mechanics is important to us. Then energy is transferred and all of you know that it flows from a so called high temperature to a so called low temperature, so heat transfer is involved. So this Troika thermodynamics, fluid mechanics, heat transfer, we tease them in this order but it is perfectly okay if you tease thermodynamics and fluid mechanics together followed by heat transfer and then you at this stage when you have completed the study of heat transfer you can say you have reasonable basic knowledge to do the real thermal engineering subjects which we call either applied thermodynamics or a better name is perhaps energy conversion. Earlier this used to be called heat and power or heat power and refrigeration but I think a small and sweeter name is energy conversion under which you talk of various processes of energy conversion as implemented in say the internal combustion engine, gas turbines, steam turbines, steam power plants, refrigeration air conditioning and its various other aspect and you can list them out. For example in this you will have steam turbines, gas turbines, you may have IC engines, you may have refrigeration, air conditioning, cryogenics, whatever. I think it is worth spending about half an hour or some such time in explaining all this because you know what I find is when you look at your mechanical engineering curriculum as a whole, note there will be no subject in which it would be specifically mentioned that tell them what is engineering, tell them what is mechanical engineering and why we study mechanical engineering. Because even if you have a course in introduction to mechanical engineering I do not think there is any topic or subtopic which is mentioned, here we do not have at least today we do not have an introduction to mechanical engineering. So the mechanical engineering students the first subject they face in mechanical engineering is thermodynamics from the thermal engineering stream and I think solid engineering mechanics from the design engineering stream. There is a course in simple engineering mechanics, the Schemes book type of thing but that is typically taught in the first year, second semester and it is taught rarely by mechanical engineers quite often by civil engineers so they do not talk about the straight away going to you know free body diagrams and force balances and things like that. This may be a bit of a divergent but I think it is necessary for us at some stage. If you have a subject before thermodynamics in mechanical engineering we will do this in that subject but quite often I find that thermodynamics is if not the first one of the first subjects in mechanical engineering that a student learns typically in the second year first semester and hence it is necessary to put the whole thing in context and hopefully when you do this their interest in engineering in general and mechanical engineering in particular will be rekindled or will interest will be germinated if there was no interest and their life as students and our life as teachers will become that much more comfortable. Any comments? Heat transfer is a subset of thermal engineering, heat transfer not thermodynamics. The way we look at thermodynamics is heat transfer is a science of rates of heat transfer. So what per minute sorry joule per minute, joule per second, watt, kilowatt these are the essential units of that whereas in thermodynamics we talk about changes in a system but we never talk about the rate of change in a system. Our first law, our second law has no time in it except that second law gives us the idea of the arrow of time before and after but although we can calculate the amount of power delivered by a turbine but that is only the first law simply differentiated with respect to time and that equation if I multiply it by a factor of 2 it is okay and the scaling it up and down in time but you know rate of heat transfer that is not part of thermodynamics. In fact although heat and heat transfer is a part of thermodynamics one of the weaknesses of thermodynamics that except to tell you that well you have to provide a lower temperature for heat to go away from a system to some other system. Thermodynamics does not tell you anything about it how suppose thermodynamics is to do this you will have to transfer 100 kilojoules of heat but how to transfer that 100 kilojoules, how much area is to be provided what material is to be used and given a certain area and certain interfacing material how much time it will require for that heat to be transferred that is not part of thermodynamics that we give it to heat transfer yes it is total to total. So that is why thermodynamics has only algebraic equations there are hardly any differential equations there are differential relations somebody talked about Maxwell's relations those are perhaps the most famous differential relations in thermodynamics but there are books on absolutely fundamental thermodynamics where they do not even talk about pressure volume they talk about properties P1, P2, P3 and there it is only transition between states they will only talk about general properties only properties they will talk about are temperature, energy and entropy volume as a very special status which we will soon see when we start discussing about the definitions. No process in nature is of reversible kind right but almost every analysis in thermodynamics is based on reversible process. So the bright student is asking a question immediately right you are saying that nothing is reversible then why we are analyzing and why this assumption that every process is reversible. That is because we use the reversible process as a tool to derive things it is only a process about which we can think about it is an ideal okay. For example in mechanics you take the very first law of Newton or the so called Galileo's principle that if you have a body moving on a frictionless surface it will keep on moving in the same direction if or if no force acting on it but a good student at that time does ask but sir there is no frictionless surface friction can be reduced but cannot be made zero with gravity present everywhere there is no situation where a zero force applies and why are we talking about this law that is because that is an ideal that is a reference okay when we develop the second law in fact the idea of reversibility we will bring in only when it comes to second law and one of the things which I am going to discuss now is the structure and the way we define the things and the order in which we define the things. It is necessary for teaching of thermodynamics and good learning of thermodynamics to postpone definition of concepts which are not required at an unnecessarily early stage. For example I have done an experiment successful where as I decided that look till I finish first law for closed systems I am not going to utter the word temperature in a particular implementation I did that and one student came and told me sir I was waiting for you to utter the word temperature and it was the twelfth lecture till which I had to wait and I did not realize that so much of thermodynamics we could learn without using the word temperature. So we will do that and I think now that questions are coming up I think one of the important things for me to do is provide a structure of thermodynamics which is neat and consistent I will do that that good for me. Any other question? Yes madam. Now they have only one course and whatever Maxwell equations and all I have taught in both old and new. So that they have removed from be course and now that course is some part of that course is there in advanced thermodynamics which is part of ME thermal in Mumbai University. So what about that means Maxwell equation I found it is a. See I will tell you this big comes to a situation which we ourselves have found here and may be UVB will tell you more about it because he has been he is the incoming faculty and the outgoing faculty. If the retirement age were to be remaining at 60 this would be my last year I would have retired in another 7 months, 7 or 8 months but he will be here for may be 25, 30 more years, 30 more years right of that order see as I said mechanical engineering continues to develop and as I said in the earlier scheme of things mechanical engineering has one of those widest scopes it is very difficult to say what mechanical engineering is not. So over the years now we have included subjects like even so called traditional engineering subjects like cryogenics. When I was a student there was no formal course on controls now we have formal course on even traditional controls now we have electronics controls and we have mechatronics and then we have micromechanical engineering and now because of this wid students want an exposure to you know managing of human relations and management of businesses and all that entrepreneurship and all those things. So consequently in the 4 years and 8 semesters and may be 6 subjects every semesters there are pressures to include more subjects. So naturally they result in internal pressures of either deleting some subjects or as you said 2 subjects of thermodynamics been merged into one and some topics will have to be de-emphasized now may be Bombay University has taken a decision to de-emphasize or delete property relations or Maxwell's relations. Here we have taken a decision as to provide an exposure to all basic principles but we have compressed the applied part. For example earlier there was one actually one big course one and a half times big instead of 3 lectures a week 4 lectures a week course in thermodynamics which included a reasonably detailed cycle analysis that has gone compressed to what we have in front of us today. We had 2 courses in fluid mechanics 1 courses in fluid machinery that has been compressed into one single course heat transfer has remained now when it come came to energy conversion there were 3 full flashed core courses energy conversion 1, 2 and 3 and in some order they took care of IC engines steam turbine IC engines including introduction to combustion and all that related gas turbines steam turbines detailed description of steam power plants refrigeration and air condition all this and in IIT Bombay because we are near BA RC and enough engineering enough interest always remained in nuclear engineering we had half a course on nuclear engineering included in these 3 and this was core not any electric. Now all this thing has been reduced to one course called either what over the years it has been called energy conversion or introduction to thermal machinery or now simply applied thermodynamics am I right. So it all depends on the you know the goodness and the mental set of the members of the board of studies or whatever you have and I am fortunate here that everything takes place in that one building of mechanical engineering if I want to change something on the fly I can change it just make a case give it to HOD there is a committee called departmental undergraduate committee which meets typically once a month or so it goes through it if it is okay after that it goes to main building senate but I do not have to worry about it if DUGC says okay the dean says okay I start implementing it of course I cannot get away with murder because other people are there he will ask me why you are dropping this and somebody else why not that but these pressures are bound to happen in mechanical engineering but sometimes you know absolutely funny things happen for example I was shown a revision by some university of a mechanical engineering syllabus in fluid mechanics somebody rewrote in place of Stokes law Stokes theorem now Stokes law we know had something to do with fluid viscosity it is a semi empirical law it is not a fundamental law but it is a semi empirical law it defines our CD coefficient of drag what is Stokes theorem it is in mathematics and when a knowledgeable faculty member when he saw that asked a representative from the member of the board of studies he was asked do you mean there is a difference between Stokes theorem and Stokes law that member thought that theorem is a better word than a law more impressive word so it was Stokes law was replaced by Stokes theorem so it is good you pointed it out but you are good teachers in mechanical engineering so you should take care of such pressures but remember a given take will always be there our idea our feeling here is teach them the basics link them up to applications and leave the applications essentially to the students so for example I am not sure the students in mechanical engineering today all of them will go through the same detailed calculation of velocity diagrams in turbines but they will know about momentum transfer this is autonomous institute so no problem of setting up syllabus and delivering it to students but if we take example of Mumbai University for discussion private coaching classes is a major factor playing a major role in Mumbai University engineering so if I think that I will I will teach them very few terms related to that particular topic in the beginning lectures students are going for tuition also so a teacher teaching in Mumbai University has to bear that pressure also that student coming in my class is I have to assume that he has having an exposure to this particular subject at least the beginning level because he is going for tuition so how to handle that pressure again because if I am not able to deliver all the basic information in the first or second lectures which he is getting from some other source all of a sudden he may have an impression that or a circle which may have so this is a common problem yes I agree I agree one thing I will tell you that I have a weakness that is historical is that I have never been exposed to any other educational system rather than except an autonomous system so those the way although I have been on the advisory board of many colleges I have always been pressurizing them to do things in their own way but I can understand this game of things I will tell you one way it can perhaps be done is to assume that the passing of a course it is something the student will do if they are going to the coaching classes in which case why not teach them the way you want to teach in a very interesting way those who want to attend let them attend in fact I would prefer that instead of 60 forced attendees I would prefer to have 15 schools who are interested I think we have to live with it because that is the problem which I know is brought up by and I am sure more than half of you will be facing that problem particularly in large cities like Mumbai, Pune, Aurangabad, Kolhapur but something which is odd somewhere that but of course they are affiliated to the same college so maybe they are branches of those coaching classes in those odd places also now or maybe they even have correspondence courses things you get things by mail or you get things on the internet now I was surprised at the penetration of internet it is so fantastic even in villages you find an internet connection. So now let us conclude the introductory part of thermodynamics by talking about the contributors to thermodynamics this is historical we have already said and you should tell your students that thermodynamics is not the maktedari of any particular branch of engineering or particular branch of physics and hence historically people from all branches of science and engineering have contributed to thermodynamics tell them that one of the they have learnt in their school history geography or whatever part that in the evolution of humans one of the most important step was the ability to control fire first they realized that fire was good but they only had natural fire then somebody must have realized that by you know grinding or hitting one type of a particular stone to another you can create a spark and if there is some dead wood you can create fire there must have been lots of accidents lost of lots of people and maybe entire hutments would have been burned to char but later on they realized that if you have water surrounding it or if you douse it in water you could douse that flame so the ability to create fire and control it was one of the most important aspects in human evolution and I think our ideas of thermodynamics must have slowly started developing at that time that is fire is something good does very good things for us water is something cool it can douse fire unless it is too big if it is too big that much more amount of water is needed of course at that time science had not developed technology was very rudimentary and technology was not based on science at all so no engineering really existed later on when people started studying more about water they knew water flows water flows from a higher height to a lower height there is no natural phenomena except evaporation and condensation which will take it back naturally to that height and then people started developing pumps and valves and pipelines and naturally the idea that something is hot something is cold came up and as you said many of you have said temperature is the degree of hotness but that is not a quantitative definition we will straighten that out the significant amount will go in straightening what temperature is and what temperature is not so the idea was that if heat flows from a high temperature to a low temperature from a hot body to a cold body idea came up which we now know historically as the caloric theory of heat that means heat is some sort of a fluid it does not have a mass associated with it we cannot see it but it can flow from a higher temperature into a lower temperature without really understanding what temperature was meant a vague ideas of temperature and heat started coming up and then the first thing was engines were developed but this great soul I think he was an engineer looking after mine equipment he had engines steam engines of various kinds which job was to run pumps to dewater mines and to run trolleys of produce whatever is mined and he knew this much water is to be pumped and this much coal or firewood has to be burned so if there is a better engine a better pump less firewood is burned and then he came up with the idea of efficiency of an engine and the answer to nothing is reversible comes with the flights of fancy and the extent of thinking of Carnot at that time engines and even now engines are nowhere near reversible we are nowhere near the ideal efficiency of an engine but Carnot started thinking that what should be done to improve the engine efficiency of an engine and what type of engine will have the highest efficiency we will say insulate it well have lower friction lower leakages and you need to burn less firewood that was perhaps obvious to a good engineer and good manager of those engines and to Carnot also that was obvious but he went a step further he says which engine will have the highest efficiency and he imagined that if an engine I do not know what is ideas of reversibility were there there will be an engine which will have the highest efficiency and that engine will be the one in which I have taken care of all these so called reversibility no unnecessarily temperature differences no unnecessary leakages no unnecessary friction no unnecessary pressure difference when something is flowing so that flight of fancy of his that extrapolation of his what we call Carnot theorem today is perhaps the first formal thought in thermodynamics so when you talk of history I think we should talk of Carnot first and the answer to that student who says why are we talking of reversibility said we are always talking of reversibility as a limit that is an ideal process and we should compare everything against that that provides us a limit and ideal and when we develop the thermodynamics from one principle the Kelvin-Plank theorem we will derive so many things and Kelvin-Plank principle does not talk of reversibility, reversibility will come into picture only when we talk of Carnot theorem. So emphasize the importance of Carnot in history but then say that look Carnot was an engineer make engineer in that so be proud of it that thermodynamics started with Carnot with a make engineering but later on many physicists many chemists many engineers have contributed to our understanding of thermodynamics. Historically Clausius, Rankine, Fahrenheit, Celsius in understanding of engines, understanding of cycles, understanding of thermometer. Later on when it comes to formalizing it as a science then we have physicists like Kelvin, we had chemists like Gibbs, we had even mathematicians. In fact Caratheodori I think a French mathematician is one person who was the first to put thermodynamics in its proper mathematical form and a reasonable part of our thermodynamics will be based on the Caratheodori's form. There is another one rather unknown but that is because his work is rather esoteric another mathematician known as Jai. I think all he did was a publish a book almost thesis like mathematical principles of thermodynamics. It is totally ununderstandable. It has no derivatives, it is everything in that has to do with topology but he has provided the proper topological basis for thermodynamics and he has demonstrated that I think there are only some six basic principles on which everything is based. We will not talk much about it, we will stop with Caratheodori. These are the scientists. When it comes to engineers apart from old engineers like Carnot, Clausius, Rankine, we have engineers like Kinan and a few others who have developed ideas in engineering thermodynamics and there are of course developments from Planck, developments from Einstein. After about the first half of the 20th century, physicists and chemists have contributed essentially to the molecular aspect, microscopic aspect of thermodynamics but before that Kelvin Gibbs, Caratheodori, they have all contributed to the macroscopic of the traditional aspects of thermodynamics. So a few minutes are necessary in any lecture, in any course to give them these names just to emphasize that engineers of various kinds. One name I forgot, a physicist called Bridgman, PW Bridgman is two books. One is called The Nature of Physical Theory and another is called The Nature of Thermodynamics. Super when it comes to the discussion of the basic sciences of physics and of thermodynamics. They are nowhere near good as textbooks but I think as teachers one should definitely go through these books. When it comes to chemical engineers not really in basic thermodynamics but applied chemical engineering thermodynamic, Denbigh is a name to know. Chemical engineers will smile when you talk of Denbigh. Denbigh has contributed very, very significantly to the chemical engineering thermodynamics. In fact his thermodynamics book goes by the name principles of chemical equilibrium. When you go into it, 90% is traditional thermodynamics and of that 90% more than 60% we will understand. So that basic thermodynamics he talks about. Anything to discuss or comment on this? Van der Waals is a physicist more on the properties of fluids rather than basic thermodynamics. That way there are many who have used thermodynamics. Rayleigh is one, James Jeans is another. Many, many physicists have used. That way even you know once in a while you will come across a book not directly related to thermodynamics but there will be a section on you know the basic requirements. In that in thermodynamics in about a page, two pages will give you a basic summary of thermodynamics. Excellent one. One, two such books I will mention. One is by the Nobel laureate S. Chandrasekhar. It is the title of the book is Introduction to Stellar Structure. Everything is about cosmology. But the Karatheodori's formulation of first and second law is superbly explained in a very compact form in three pages. Similarly, there is a book on book by Boli and Weiner. Maybe I should write this down. You are going to get a if not paper at least an electronic copy of this theory of thermal stresses. But in the very first chapter he has about maybe ten pages on the required thermodynamics and very nicely explained. So that brings us to more or less to the end of the introductory topics. Here we have just talked about the history, links, books, what is good, what is bad and although but I do not think any course content will say that say about this. Even our course content does not say but I find it is good to do this. Provides a proper historical background. And naturally I am doing this in thermodynamics. One day you may be teaching solid mechanics for all you know. Something similar you should do the introduction to engineering, introduction to mechanical engineering. Instead of place of thermodynamics in mechanical engineering you talk of place of materials, their strength, properties of solids in it and go ahead from there. And I am sure you have contributors, you know young, Timoshenko and all those, you have all these top contributors there. Any subject you teach spend half an hour providing a historical introduction. You should do it in whether thermodynamics, fluid mechanics, brake transfer, whatever. So let us break 14.