348 Mr R. Aclie's Experiments with Thermo- and 



The annexed figure represents a tliermo-electrical series of anti- 

 mony-bismuth bars, combined to be used for developing thermo-electri- 

 city by solar or astral radiation. 



rig. 1. 



a, a, a, a, represent 20 bars of antimony, ^ inches long, by three six- 

 teenths of an inch square. 6, 6, h, 20 bars of bismuth, 44 inches long, 

 three-sixteenths of an inch square. 



Slips of brown paper coated with shell-lac, intervene betwixt each 

 bar, so as to insulate the metals in every part, excepting their soldered 

 joints. ; y- 



The shell-lac also serves as a cement to bind the bars together. 



c, the pole attached to the antimony, e, the first joint, d, the pole 

 attached to the bismuth. 



In this arrangement, the electricity circulates through 40 bars, 44 

 inches long each, or 180 inches is the length of the combined metals. 



The thermo-electric battery (fig. 1,) can be employed as a me- 

 teorological instrument to shew the amount of radiation to or from 

 the earth ; for this purpose it has to be fixed in an exposed situation, 

 with the lower half screened from the sun and sky ; wires soldered to 

 the poles are then led to a galvanometer fixed inside of a house, when 

 the wires are 15 feet long ; the clear summer's sun turns the magnets of 

 the galvanometer nearly to a right angle ; while astral radiation, under 

 favourable circumstances, deflects them in an opposite direction 26 or 

 30 degrees. The arrangement described is remarkably sensitive to thin 

 vapours passing over the sky ; and even with the galvanometer, 40 feet 

 distant from the battery, the indications are sufficient to furnish a scale 

 which will enable an observer on inspection to judge of the rate of 

 radiation to or from the earth. 



The battery with projecting radiating ends appeared to me to admit 

 of application to generate currents of the lightest thermo-electrical in- 



