12 PIONEERS OF SCIENCE IN AMERICA. 



the properties and powers of frictional electricity, now familiar, 

 but in those days original and startling discoveries. The bril- 

 liancy of these experiments, said Dr. J. W. Holland, of Jefferson 

 Medical College, at the centennial commemoration, " depended 

 mainly on Franklin's discovery that the electricity of the Ley- 

 den jar was stored up on the glass, and that by increasing the 

 extent of excited surface the energy was proportionately multi- 

 plied. The power thus obtained made it appear highly prob- 

 able that the difference between the spark and the lightning 

 flash was one of degree " as was ultimately proved. " In a 

 hundred years," Dr. Holland adds, " but little has been added to 

 what Franklin revealed concerning the electricity of friction." 

 In a paper read before the Royal Academy of Sciences at Paris, 

 in 1779, Franklin gave an explanation of the aurora borealis 

 as a phenomenon of atmospheric electricity which still holds 

 good as to its general principles, although the details have 

 been modified by recent discoveries ; but he does not seem to 

 have grasped the connection between electricity and magnet- 

 ism, for, in a letter written in 1773 to M. Dubourg, in Paris, he 

 gives it as his " real opinion that these two powers of Nature 

 have no real affinity with others, and that the apparent produc- 

 tion of magnetism [by electricity] is purely accidental "; and 

 he gives ten points in explanation and proof of this view. 



The next most important of Franklin's labours in the field 

 of practical science is represented, perhaps, by his invention 

 of a stove and his study of the causes and cure of smoky 

 chimneys. The Franklin stove was not merely the porta- 

 ble open grate or fireplace with which the name is usually 

 associated, but was a philosophically constructed heating ap- 

 paratus, based upon a careful study of the properties of 

 warm air and the diffusion of heat, and embodied the principles 

 which have since been applied in endless variety in the con- 

 struction of stoves of every shape and of hot-air warming 

 apparatus. He further devised a stove in which all the 

 smoke was turned to account and operated as fuel in heating 

 the rooms, which, when tried, answered even beyond his ex- 

 pectations. His studies of smoky chimneys furnished a remedy 

 for what was in his day one of the most crying miseries of 

 domestic life. Connected with this subject is that of ventila- 

 tion to which he gave much attention ; and he is credited with 

 being the first person who observed that respiration communi- 



