M. Arago's Biographical Memoir of James TFatt. 265 



the weight of our body to the height of Mont Blanc. This 

 labour, or an equivalent to it, is executed by a steam-engine 

 with the consumpt of two pounds of coals. It has thus been 

 established by Watt, that the daily power of man does not 

 exceed that which is contained in a pound of coal. Again, 

 Herodotus informs us, that the construction of the Grand 

 Pyramid of Egypt employed one hundred thousand men during 

 the space of twenty years. The pyramid is formed of lime- 

 stone ; its volume can easily be calculated ; and hence it is de- 

 duced that its weight is about thirteen millions of millions of 

 pounds. To elevate this weight to the height of one hundred 

 and twenty-five feet English, which is the height of the centre 

 of gi-avity of the pyramid, it would be necessary to consume 

 under the boiler of a steam-engine 630 chaldrons of coal ; 

 and I could name a foundery in Britain which consumes a 

 greater quantity every week. 



Copying Press — Heating by Steam — The Composition of Water — 

 Bleaching by means of Chlorine — Experiments upon the Physio- 

 logical Effects resulting from the Respiration of various Gases, 



Birmingham, when Mr Watt went to establish himself at 

 Soho, reckoned among the inhabitants of the neighbourhood, 

 Priestley, whose name is universally known ; Darwin, the cele- 

 brated author of the Zoonomia, and of a poem, " The loves of 

 the Plants ;" Withering, a physician and distinguished bota- 

 nist ; Keir, a chemist well known by the Notes of his transla- 

 tion of Macquer, and by an interesting memoir on the Crystal- 

 lization of Glass ; Galton, to whom we are indebted for an 

 elementary treatise on Ornithology ; and Edgeworth, the au- 

 thor of several esteemed works, and father of the celebrated 

 Maria Edgeworth. These scientific men speedily became the 

 friends of the distinguished mechanist, and most of them 

 united in forming with him and Mr Boulton, an association 

 under the name of " The Lunar Society.'''' This fantastic title 

 has given rise to various mistakes ; but it imported nothing 

 more than that the night of meeting was that of the full moon, 

 a time selected, in order that the members might comfortably 

 reach their several domicils. 



Every meeting of the Lunar Society gave fresh occasion, to 



