MODIFIED ly COMPRESSION. 85 
being filled with pounded filex, or with whatever occurred 
as moft likely to prevent the intrufion of the fufible metal 
in its liquid and penetrating ftate. This tube fo filled, was: 
placed in a frame or cradle of iron (df 4, figs. 3, 4, 5, and 
6,) fixed to the end (m) of a ram-rod (mm). The cradle 
was from fix to three inches in length, and: as much in diame- 
ter as a gun-barrel would admit with eafe. It was compofed 
of two circular plates of iron, (def g and 4 k /, feen edge- 
wife in the figures,) placed at right-angles to the ram-rod, one 
of thefe plates (def 4) being fixed to it by the centre (m). 
Thefe plates were connected together by four ribs or flattened 
_ wires of iron.(d 4, ¢ i, f &, and.g /,) which formed the cradle 
into which the tube (A), containing the carbonate, was intro- 
duced by thrufting the adjacent ribs afunder. Along with the 
tube juft mentioned, was introduced another tube (B), of iron 
or porcelain, filled only: with air. Likewife, in the cradle, a: 
pyrometer:* piece (C) was placed in _conta& with (A) the tube 
containing the carbonate. Thefe articles generally occupied. 
: the 
Fe Tar, pytometer_pieces rae ans shel experiments were made under my own- 
eye: Neceflity compelled me to undertake: this laborious and difficult work, in. 
which Ihave already fo far fucceeded as to obtain a fet of pieces, which, though 
far from complete, anfwer my purpofe tolerably well. I had lately an oppor- 
tunity of comparing my. fét-with that of Mr WepcGwoop, ati various tempera~ 
‘tures, in-furnaces of great fize and fteadinefs. The refult has proved, that my- 
pieces: agree as well with.each other as_his; though with my fet each tempera- 
ture is indicated by a different degree of the fcale. I have thus been enabled to 
conftru& a table, by which my obfervations have been corre@ed, fo that the 
temperatures mentioned inthis paper are fuch as would have: been indicated by 
Mr WeEpnGwoop’s pieces. By Mr WepGwoon’s pieces, I mean thofe of the. 
only fet. which, has; been fold to the public, and byrwhich the melting heat of 
pure filver is indicated at the 22d degree. I am well aware, that the late Mr 
WepcwooD, in his Table of Fufibilities, has ftated that fufion’ as taking place at _ 
the 28th degree; but I am convinced that his obfervations muft-have been mede. 
with fome fet different from that which was afterwards fold, 
