Mycroft paused to take a liberal gulp of a brandy he was nursing while he lectured. “Thermodynamics is derived from two Greek words, thermos, meaning heat and dynamics, meaning work. Thermodynamics is simply the science of heat and work, and the relationships between the two as laid down in the Laws of Thermodynamics. It is the effects of changes in temperature, pressure, and volume on physical systems. Heat means "energy in transit" and dynamics refers to "movement". So, thermodynamics examines the movement of energy and how energy instills movement. Historically, thermodynamics has developed out of need to increase the efficiency of steam engines. “Thermodynamics was given a molecular interpretation. This field is called statistical thermodynamics, which can be thought of as a bridge between macroscopic and microscopic properties of systems. Statistical thermodynamics is a method of thermodynamics based upon statistical mechanics, which result from macroscopic consequences. “I really do not understand that last statement, but let me proceed. “An important concept in thermodynamics is the ‘system’. A system is the region under study. A system is separated from the remainder of the world by a boundary which may be imaginary or not, but which by definition sets a finite volume. The possible exchanges of work, heat, or matter between the system and the surroundings take place across this boundary. “ The central concept of thermodynamics is that of energy, the ability to do work, as in driving a steam engine while hauling carriages, setting a battleship to sea, or shooting a cannon shell to sink said ship. As stipulated by the first law of thermodynamics, the total energy of the system and its surroundings is conserved. It may be transferred into a body by heating, compression, or addition of matter, and extracted from a body either by cooling, expansion, or extraction of matter. For comparison, in mechanics, energy transfer results from a force which causes displacement, the product of the two being the amount of energy transferred. In a similar way, thermodynamic systems can be thought of as transferring energy as the result of a generalized force causing a generalized displacement, with the product of the two being the amount of energy transferred. “There are two types of thermodynamic instruments, the meter and the reservoir. A thermodynamic meter is any device which measures any parameter of a thermodynamic system. A thermodynamic pressure reservoir is a system at a particular pressure, which imposes that pressure upon any test system that it is mechanically connected to. “We now believe that the technical equipment ordered by the M Agency and delivered to a location deep in Germany hidden from our eyes were thermodynamic meters and specialized high pressure reservoirs. No more than one sub-unit was ordered from any one company, but several incomplete units were shipped separately, which could be combined on the receiving end without the shipper even being aware of what else his part was fixed to. “Our industry is using many forms of high hydraulic pressure. A force acting on a small area can create a much larger force by acting on a larger area by virtue of hydrostatic pressure. Therefore, a very large amount of energy can be carried by a small flow of highly pressurized fluid. “The series of lectures being attended by Bob Catesby are concerned with practical application of thermodynamic principles as applied to extreme high fluid pressures. A mathematician may dream up anything he pleases, but a physicist must be, at least to a degree, sane. And an engineer must design that sanity into a workable device. "Sherlock, what I vaguely am groping toward is that Moriarty is seeking to develop a high pressure weapon that can be employed against our naval forces, in particular the cream of our battleships, the newly commissioned HMS Dreadnought. He has already refined and employed a remarkably powerful air rifle. Perhaps he is seeking to develop an aquatic version of that gun.” “Do you believe he needed the unique meteor that was stolen to manufacture a new dense metallic shell to perforate the battleship’s armor?” I risked. “I do not know,” Mycroft finished his brandy in a last swallow, set down the glass and said, “ but I am determined to find out. We need to break into his house and find his plans and notes if they are kept there. We cannot