ON THE HISTORY OF TERRESTRIAL PHYSICS. 74*) 



The foundation of the most celebrated of the philosophical societies of Eu- 

 rope renders the latter half of the seventeenth century a very interesting pe- 

 riod in the history of natural knowledge. The Royal Society of London, and 

 the Academy of Sciences of Paris, have always been the most distinguished 

 of these: and the Florentine Academy del Cimento, although its labours were 

 not of long duration, produced at first in a short time a very copious and in- 

 teresting collection of experiments, relating to various subjects of physical re- 

 search. In the Royal Society, Boyle, Hooke, and Newton were the most industri- 

 ous, as well as the most successful investigators of natural phenomena : the ele- 

 mentary doctrines of chemistry, the nature of combustion, the effects of heatand 

 cold, and the laws of attraction, repulsion, and cohesion were attentively examin- 

 ed and discussed. The expansion ol water, by a reduction of its temperature, near 

 the freezing point, was first observed by Dr. Croune ; although his experi- 

 ments were considered by Dr. Hooke as inconclusive. The attention of the 

 society was directed by Newton to the phenomena of electricity, some of 

 which had been a short time before particularly noticed by Guericke'; the 

 mode of making electrical experiments was greatly improved by Hauksbee; 

 this accurate observer investigated also the nature of capillary attraction 

 with considerable success. Early in the succeeding century, many of the 

 members of the Academy of Petersburg followed the example of other so- 

 cieties with great industry; and the experiments of Richmann on heat were 

 among the first and best fruits of their researches. 



Dr. Halley employed himself, with the most laudable zeal, in procuring in- 

 formation respecting the variation of the compass; he undertook a voyage 

 round the world, for the express purpose of making raagnetical observations ; and 

 he published a chart of variation, adapted to the year 1700. He also collected 

 many particulars respecting the trade winds and monsoons, and he endea- 

 voured to explain them by a theory which has been adopted by some of the 

 latest authors, but which is in reality nmch less satisfactory than the hy- 

 pothesis proposed some time afterwards by Hadley. His magnetical investi- 

 gations were continued with great diligence by Mountaine and Dodson, who 

 published, at different periods, two charts representing the successive states of 

 the variation. Euler, Mayer, and others have attempted, in later times, to 

 discover such general laws as might be sufficient to determine the magnitude 



VOL. I. 5 a 



