xxviii. Proceedings. [January 26th, 1897. 



drive the instrument at night. During the months of May, 

 June, and July last, such a storage instrument continued in 

 motion without stopping day or night ; and in fine climates, 

 like Egypt, much longer periods of continuous movement 

 could undoubtedly be secured. The speed of the instrument 

 is affected by barometrical pressure and hygroscopic condi- 

 tions. It is capable of marking the dew-point, and works 

 well, even when its glass shade is completely coated with 

 ice, or half-buried in snow. Mr. Bennett has succeeded in 

 adapting the instrument to act as a calorimeter by first 

 cooling the whole of the instrument to a given tempera- 

 ture, when rotation ceases, and then suspending pieces of 

 heated metal inside. In this way the specific heats of 

 substances can be accurately compared, since the number 

 of rotations caused is in direct proportion to the amount 

 of introduced heat. The instrument can also be used to 

 measure the comparative heat-retaining power of textile 

 fabrics, boiler compositions, &c, and the relative heat con- 

 ductivities of thin threads and wires. Mr. Bennett has also 

 instituted a series of experiments, as yet incomplete, into 

 the comparative sensitiveness to convection effects of various 

 gases, which promise interesting results, since the differences 

 already noted are unexpectedly great, and, moreover, do not 

 bear any direct relation to the densities or other known 

 physical properties of the gases tried. 



