51 
the graphic art, such as post office and receipt stamps, and 
other prints that are required in greater numbers than could 
be produced by other than steel plates or stamps. His 
system of engraving on steel has at length become a great 
artistic power, the wide-spread increase of which has given 
employment to labour and capital to a vast extent in the 
several branches of art before stated, and from which I 
believe many large fortunes have been made, hut little other 
than “ toil and trouble” ever accrued to the inventor of them. 
When any important discoveries in physical science are 
made they never die, whatever may chance to their authors. 
The new facts brought before the public go forth like seeds 
cast upon a fertile soil, yielding the fruits of continual pro- 
gress among the families of men who seek improvement. It 
seems only just then that each generation should transmit to 
the next some record of the names of those contemporaries to 
whose genius and talents all nations are indebted for such 
discoveries. Wherefore, in addition to the four distinguished 
inventors brought to the notice of this Society in my former 
papers, I have "in the present one aimed to place that of 
Jacob Perkins as a worthy contributor to the advance of 
those branches of art to which his inventions have been 
applied. 
Appendix I. 
On the Compression of Water. 
In tracing the progress of steel engraving I had no thought 
of giving a general account of Mr. Perkins’ researches in 
physical science, yet it may not be out of place to notice one 
or two other of his discoveries. 
(1) His experiments on the compressibility of water (made 
some time before he left America) were to test the correctness 
of the doctrine founded on the Florentine experiments, that 
water was a non-elastic body, which was then generally 
taught in the schools and elementary works. At that time 
