SEVEBAL MECHANICAL INVENTIONS. 171 



former length, raising the piston, and marking the greatest 

 compression effected. 



Fourth, in each trial the diminished bulk of the water 

 corresponded with the increased force applied ; and it was 

 found that under the pressure of lOO atmospheres the bulk 

 of water was reduced one part in a hundred, and this rate, 

 as before mentioned, was the same as had been shown by 

 the experiments of Canton. 



Some time after the experiments of Perkins had been 

 repeated and publicly shown in London, a course of similar 

 experiments were made by Professor CErsted, who em- 

 ployed a stout glass vessel, and adopted a column of mer- 

 cury to give the pressure, having the like inside instru- 

 ments to mark the results. These being the same as those 

 shown by Canton and Perkins, go to confirm the said law 

 of compression. 



APPENDIX II. 

 On Perkins's Steam-Chin. 



Among the interesting inventions of Mr. Perkins were 

 those for substituting high-pressure steam in place of gun- 

 powder for small arms and artillery, so as to discharge pro- 

 jectiles with far greater rapidity and destructive effect from 

 batteries on sea and land, than could be done by any 

 system of gunnery then in use. This scheme attracted 

 great public attention at the time it was brought out (in 

 1821). 



To carry this object into effect, Mr. Perkins had devised 

 a plan for subjecting water to a more intense heat than 

 could be done by any of the boilers then known. He em- 

 ployed a great number of strong iron or copper tubes, 

 placed near together, with their ends fastened into iron 

 plates, and these fastened to other end-plates, formed 



