98 Description of the Steam Pyrometer. 
is four inches, leaving a space of three fourths of an inch to be filled 
with finely powdered charcoal or lampblack, seen at O, in the sec- 
tion (Fig. 2.) 
The interior cylinder rises half an inch above the exterior, which 
is twelve inches high. The former*is then expanded into a funnel- 
shaped mouth, F, five inches in diameter at top, and two inches per- 
pendicular height, intended to receive and return any portions of 
water which might be thrown up by ebullition, but not converted into 
steam. From the lower part of the apparatus a third concentric 
cylinder, K, rises about three inches and one fourth, where it termi- 
nates in a conical head furnished with a pipe, P, passing obliquely up- 
wards through the two cylinders before mentioned, and firmly solder- 
ed to both. The purpose of this third cylinder is to receive the 
lamp L, and to expose a large surface to the action of its ame. eis 
a stopper intended to close the pipe, P, when the lamp is withdrawn 
and the experiment in progress. E is an index attached to the sup- 
port m, in such a manner that the point E, may be elevated or de- 
pressed a few degrees, to correspond to the position of the beam D, 
and save the adjustment by weights before an experiment. ‘The cyl- 
inder of lead C, is movable along the rod by means of a screw thread, 
cut the whole Jength of that arm. This mode of adjustment admits 
of the greatest accuracy, and is liable to less delay than the sliding 
weight. By means of the tightening screw ¢, the support mm, may 
be placed at any convenient height on the rod 7, and by means of s, 
the lamp L, may be loosened and caused to revolve [horizontally 
when the metal is about to be immersed; in which case the boiler 
will be for the time depressed, and will rest on the cushion B, which 
is composed of hare’s fur, covered with soft flannel to defend the 
bottom from the access of air; the stopper e, is a further safeguard 
against the same source of loss. A thermometer g, bent at mght 
angles, passes through the two concentric cylinders, having the bulb — 
directly exposed to the water within, but defended from injury by a 
projection of its tube 0, a short distance beyond the inner cylinder. 
The receiver R, is about four inches in height, and one and a quar- 
ter in interior diameter, furnished above with a tube /, and a stop cock 
k, to convey away the steam, and to carry it, when required, into a ves- 
sel of cold water. The only direct access of the water «, to the hot 
body I, when in place, is through the bottom of the receiver. If the 
stop cock be closed the steam will soon fill all the surrounding space 
and keep the water down quite to the lower edge, but if the cock be 
opened, the steam finding an outlet will rise, and the water will fol- 
low and again produce a large quantity of vapor. It will generally 
