258 MR. J. C. DYER ON SEVERAL MECHANICAL INVENTIONS. 



business talents that appeared in the management, as also 

 from some differences about the capital in the concern, I 

 was induced to consent to an outright sale to the Company 

 of my contingent share of its profits at a price which did 

 not exceed what my share ought to have produced per 

 annum, if the affairs had been conducted with judgment 

 and prudence. I refrain from naming any of the parties, 

 and have merely stated the above facts in justice to my- 

 self and to my friends in America before mentioned. 



The principal movements in the nail- machine were given 

 by the crank, lever, and wedge actions in common use, and 

 therefore require no special notice ; but in that invented 

 by Mr. Perkins the heading dies were worked by what he 

 called a " Toggle-joint," this being the finger-joint. It 

 was suggested to him by observing the process of laying 

 down floor-boards by carpenters : — that of nailing down 

 two boards at some distance apart and placing several loose 

 boards between them ; then, bringing the edges of the latter 

 together, they are pressed down between the fixed boards 

 with a force that pinches them into the smallest prac- 

 ticable space without crushing the wood. This joint acts 

 upon the principle of the wedge, with two circular faces 

 meeting at the tangent to the circle, and thus acting 

 like a pair of rollers, to pinch or press any body brought 

 between them with a force limited only by the rigidity of 

 the meeting faces. Now this force was found very efl&cient 

 in pressing the ends of large nails into the several forms 

 of heads required, and is here referred to because it has 

 been since adopted and found very efl&cient in riveting- 

 machines for making steam-boilers, bridge-girders, and in 

 some others of recent invention. 



The new system of nail-making, originating as above 

 stated, has been so widely extended as to give profitable 

 employment to many thousands of workmen, and to supply 

 an important article of very extensive use, both for home 



