37 ^ 
Steam Engine^ 
ing a draft, was made of rolled iron ; and the steam, which 
wholly escapes from these machines uncondensed,, was 
conducted into the same tube, about a foot above its in- 
sertion into the boiler ; therefore many feet from the fire, 
and beyond the register. When the engine began to 
move, it was soon remarked that neither steam nor smoke 
were seen to issue from the flue : and when fresh coal 
was added, nothing more than a faint white cloud be- 
came apparent, and that only for a short time ; nor were 
drops or mist visible any where. It was proposed, that 
the register should be slowly closed ; and as this was 
done, a condensation of steam manifested itself at a small 
distance front the chimney, and finally appeared in the 
same quantity, as if it had proceeded immediately from 
the boiler. The experiment was then reversed. The 
steam was gradually confined to the boiler ; when smoke 
became more and more visible, till it equalled in quanti- 
ty and appearance that commonly produced by a similar 
fire : and these trials were alternated a great number of 
times, with unvarying success^ Lastly, it became a mat- 
ter of speculation, whether or in what degree the draft was 
affected by the admission of steam into the flue. To as- 
certain this, every one present looked as attentively 
as possible into the fire-place ; while the en gine 
moved at the rate of a few strokes in a minute ; and all 
agreed in declaring, that the fire brightened each time 
the steam obtained admission into the chimney, as the 
engine made its stroke. 
I am, Sir, 
Your very faithful humble servant, 
DAVIES GIDDY. 
(12 Ntchalso7i*s Journal^ p. 1.) 
