166 REPORT — 1856. 



the loss of heat occasioned by the use of steam, and which had been variously esti- 

 mated from tV to xj of the heat transmitted, might be avoided, and that we should 

 ultimately discover a more economical medium. All these attempts have as yet 

 been arrested by practical difficulties which have been encountered, but which may 

 yet be obviated. 



The dynamical theory of heat has, however, been more recently developed by 

 Mayer in 1842*, and Helmholtz in 1847, and greatly extended by Messrs. Rankine 

 and Thomson about the same period. Mr. Siemens, in his paper " On the Conversion 

 of Heat into Mechanical Effect," published in the second part of the twelfth volume of 

 the ' Transactions of the Civil Engineers,' in citing proofs against the material theory 

 of heat shown by the experiments of Davy and Dulong, says, that, " inasmuch as they 

 show an intimate connexion between heat and the mechanical force by which it was 

 produced, and according to which heaf, mechanical force, electricity, chemical affi- 

 nity, light and sound are but different manifestations of one great and infinite cause, 

 motion f, — the specific heat and temperature of a body determine the vibrating 

 velocity of the material particles, the square of which multiplied by the weights of 

 the particles gives their inherent force or vis viva. In solids, the vis viva is least 

 remarkable ; in fluids it is greater. In gaseous fluids, it predominates so strangely 

 over gravitation that the latter force becomes inapplicable." 



Mr. Siemens gives the following as the results obtained in units of power or foot- 

 pounds for one unit of heat by different authors : — 



Centigrade Fahrenheit's 



Thermometers. Thermometers. 



By Holtzman's formula 1227 foot lbs. 682 foot lbs. 



By Joule's experiment 1386 „ 770 „ 



By Rankine's formula 1252 „ 695 „ 



By Thomson's „ 1390 „ 772 „ 



By the best Cornish engine, according to 



Bambur 148 „ 82 „ 



By a perfect low pressure and condensing 90'8 ,, 50-4 „ 



By an actual Bolton and Watt's engine. . 46 „ 25'5 ,, 



The above Table is further illustrated b}' a table showing the theoretical and an 

 actual performance of steam- and air-engines by diagrams showing the curves which 

 would be indicated theoretically by converting heat into dynamic effect. 



In March, 1856, being at Southampton, it occurred to me to make an experiment 

 on the difference of temperature between the water in the tidal basin of the docks 

 there, and the water then running through the sluices of the iron gates of one of the 

 dry docks which was then filling for the purpose of letting out a vessel into the tidal 

 basin. The result was a difference of two degrees. In both cases the same thermo- 

 meter was suspended ten minutes in the water of the tidal, and afterwards iu the 

 current of water running through the sluices into the dry dock. Observations on 

 the temperature of the sea in stormy weather, and through water-wheel races, always 

 indicated an increase. 



Being desirous of corroborating these statements, a box or cistern made of deal, 24 by 

 22J inches square, and 20 inches deep, was prepared ; a quantity of Thames water, 

 about 20 inches in depth, was poured into it, equal to 4375- lbs. Into the side of the 

 box was fitted a bent iron tube of 2 in. diameter ; and into the upper part, above the 

 bend of the pipe, a glass tube was inserted ; so that, by suspending a glass thermo- 

 meter in the water contained in the tube, the temperature could be easily seen. 



The box was then covered by a wooden lid, so closely fitted as to exclude the sur- 

 rounding air, and to prevent the loss of water by agitation. A wooden spindle 

 having four arms, and twelve vertical agitators, was previouslj' fitted into the lid of 

 the box, as shown by the accompanying woodcut ; a pulley of wood was fitted to the 

 top of the spindle ; and the apparatus was rapidly revolved in the water by being 

 connected with a steam-engine. 



* Mayer was the first to observe an increase of temperature of from 12° Centigrade to 13° 

 Centigrade by agitating water in the year 1842. 



The remarkable experiments of Beaumont and Mayer in the boiling of 400 litres of water 

 by the friction of a roller revolving in the interior of a tube, in the middle of a boiler sur- 

 rounded by water, 1855, at the Paris Exhibition, show the effects of mechanical force, 

 f Correlation of Forces, by Grove. 



