$ INVISIBLE EMISSION OF STEAM AND SMOKE. 



of rolled iron ; and the fteam, which wholly efcapes from thefe 



machines uncondenfed, was conducted into the fame tube, 



The fteam was about a foot above its infertion into the boiler ; therefore many 



lifter worki 



thrown into the ^ eet ^ rom tne ^ re » an d beyond the regifter. When the engine 

 chimney m»ny began to move, it was foon remarked that neither fleam nor 

 £ re# fmoke were Teen to iflue from the flue : and when frefh coal 



Neither fmoke was added, nothing more than a faint white cloud became 

 wlfibJe!* 01 WWC a PP arent > and that only for a (hort time ; nor were drops or 

 mift vifible any where. It was propofed, that the regifter 

 When the (hould be flowly clofed ; and as this was done, a condenfation 



off the fteam or " ^ eara manifefted itfelf at a fmall diftance from the chimney, 

 was vifible, and and finally appeared in the fame quantity, as if it had pro- 

 was fliut oft' the ceec * e d immediately from the boiler. The experiment was 

 fmoke was vi- then reverfed. The fteam was gradually confined to the 

 lc# boiler; when fmoke became more and more vifible, till it 



equalled in quantity and appearance that commonly produced 

 by a fimilar fire: and thefe trials were alternated a great 



The draft up number of times, with unvarying fuccefs. Laftly, it became 

 the chimney was r r .' . , ,, . , . ,,/» 



increafed by the a matter or Jpeculation, whether or in what degree the draft 



admiflion of the was affected by the admiflion of fteam into the flue. To 

 afcertain this, every one prefent looked as attentively as 

 poflible into the fire-place; while the engine moved at the 

 rate of a few ftrokes in a minute; and all agreed in de- 

 daring, that the fire brightened each time the fteam ob- 

 tained admiflion into the chimney, as the engine made its 

 ftroke. 



I am, Sir, 



Your very faithful humble fervant, 



DA VIES GIDDY. 



II. 



On a Meteoric Stone that fell in the Neighbourhood of Sigena, 

 in Arragon, in 1773, by Profejfor Proust*. 



Stones have JL HE author begins his paper by fome previous hiftorical 



fallen from the f ac i s . N one novv queftions, that ftones have fallen from. 



atmofphere ta> , , 1- . ..S 1 ' , , , _, 



various ages, » ie atmofphere in different parts of the world. The ancients 



* Abridged from the Journal de Phyfique, for March 1805. 



mention 



