MEMOIR OF DANIEL TKKADWELL. 



813 



arrangement or organization I leave to others to determine. I can only say that the motions 



are produced by machinery the most simple in my power to contrive." 



The principles and reasoning so clearly expressed in this example of <rood writ- 

 ing upon a combined mechanical and physiological subject were carried out in a 

 press constructed in 1S18, differing from the ordinary hand-press in many respects. 

 In the latter, the "form" of type is upon a movable " table " or carriage, on which 

 it can be run in and out beneath the platen, a plain piece of solid wood or metal 

 covering the face of the form, and which, when pressed down by a powerful screw 

 and lever pulled by the arm of the workman, gives the impression to the paper. 

 In Mr. Treadwell's press the form is stationary, and the platen, which is light, with 

 its tympan and " frisket," turns upon a horizontal hinge, and is so counterbalanced 

 that it can be turned on and off the form with very little force. The impression is 

 given by a lever, which rests upon projecting pieces of metal rising from the top 



of the platen. This lever is connected by a descending rod with a treadle near the 

 floor; upon this the pressman treads with his whole weight, and, thus straightening 

 the "toggle joint,"* brings down with great force the platen upon the types. The 

 time and power lost in moving the form are saved, and the muscular effort is a ste] 

 instead of a pull. To this is added, by means of a double frisket, a mode of revers- 

 ing the sheet applicable to half-sheet work, so that it may be printed on both 

 sides without shifting. This was called the " Treadle " or " Foot Lever Pre--*." The 

 construction and manner of working will be understood from the following descrip- 

 tion and illustrations, taken from Hansard's Typographia, p. 659. 



"Figure 1 represents a side view, with the tympan and the frisket folded upon the platen, 

 and the platen turned down upon the form. Figure 2 represents a front view, with the platen 



turned up off the form, and the frisket open. The action of the press is as follows. 



" Having placed the sheet of paper to be printed upon the tympan, a, fold down the frisket, 

 b, upon it as usual, and then turn over the platen, c, down upon the form, </, as seen in fig. 1. 

 To obtain the pressure, the workman then steps upon the treadle, e, which brings down the 

 bar,/, and by means of the knee-joint, a* the arms h and i become straightened, and con- 



* Mr Treadwell gives the following account of the origin of the toggle-joint, or "knee-joint," now so com- 

 monly used in machinery : 



"The toggle-joint, although to be found in principle in the crank and connecting rod, and in many other 

 combinations, was first brought into use, in its present distinct form, by Mr. Jacob Perkins, of Newlmryport, 

 Mass., about the year 1800, or a little before that time, in the nail machine then invented by him. It was 

 hardly known to the English machinists in 1820, who, on adopting it, _ ive it the name of the 'end lever.' The 

 name toggle-joint was said to have been given by Mr. Paul Moody, who commenced his career as a workman of 

 Mr. Perkins, and ended it as chief engineer of the works at Lowell, of which city he was one of the principal 

 founders. Mr. Wells might have been the first to use the toggle-joint in its simple form in the printing-press; 

 but Medhurst had made a very near approach to it in his press, invented not long after the date above assigned to 

 the distinct introduction of it in the nail machine." 



