Royal Society. 167 



and particularly that of its availability on an extensive scale. The 

 power is peculiarly fitted for purposes of navigation, if it can be 

 made subservient ; and a trial upon a scale of 100 horse power 

 seems to be the only mode of arriving at a definite conclusion upon 

 this point. It is obvious that, preliminary to such an undertaking, 

 a great many experiments will be absolutely necessary ; and such 

 only as one quite familiar with the difficulties of entering upon an 

 entirely new field of operation can properly appreciate* . 

 I have the honour to be, most respectfully. 



Your obedient Servant, 

 Hon. Wm. A. Graham, Chas. G. Page. 



Secretary of the Navy. 



XXII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 75.] 



May 30, IVI R* WELD communicated the following particulars 



1 850. i~^^ respecting the original model of the safety-lamp which 



was presented to the Society at this meeting by Joseph Hodgson, 



Esq., F.R.S. 



In November 1815, Sir Humphry Davy read a paper before the 

 Royal Society ' On the Fire damp of Coal Mines, and on Methods 

 of lighting the Mines so as to prevent its Explosion.' In this commu- 

 nication he described a safe light. " which became extinguished when 

 introduced into very explosive mixtures of fire-damp:" but as this 

 fell short of the philosopher's wishes, he instituted a fresh series of 

 experiments, which resulted in his invention of the safety-lamp, 

 described in a paper read before the Society in January 1816. 

 "The invention," he says, "consists in covering or surrounding the 

 fiame of a lamp or candle by a wire sieve;" and he adds, "when a 

 lighted lamp or candle screwed into a ring soldered to a cylinder of 

 wire gauze, having no apertures except those of the gauze, is intro- 

 duced into the most explosive mixture of oarburetted hydrogen and 

 air, the cylinder becomes filled with a bright flame, and this flame 

 continues to burn as long as the mixture is explosive." The model 

 in the possession of the Royal Society answers in every respect to 

 this description, and to the representation of the lamp which accom- 

 panies the paper. It was made by Sir Humpliry's own hands, and 

 given by him to Dr. Lee, now Lord Bishop of Manchester, whose 

 father was Assistant Secretary to the Royal Society at the time of 

 Davy's Presidency. The excessive simplicity of the contrivance is 

 most remarkable ; but this is one of the greatest advantages which 

 attended the invention. As the author remarks in the paper just 



* In a letter to the Editors of the American Journal of Science, dated 

 October 14, 1S50, Prof. Piijre states, " My engine has now reached 10 horse 

 power. The data are as follows : — Engine, two-feet stroke ; tiy-wheel, 13"29 

 feet in circumference, 102 revolutions with 1900 pounds pressure upon its 

 periphery." 



