136 [Assembly 



journals, that the book, by means of a crank, may be so turned 

 as to present any part of the back to the face of the roller. A 

 steel roller, two Inches in diameter, and corresponding in length, or 

 nearly so, to the length of the book, and parallel with it, is held 

 between two movable brass boxes, by a shaft passing through the 

 centre of the roller, and through the boxes, serving as a journal 

 on which the roller is turned. When raised from the book, 

 this roller is about half an inch above the back, inclined a little 

 on one side. Two sliding gages, shaped to the back of the book 

 are placed immediately above it, and in front of the roller, and 

 when tlie book is inserted between the jaws from underneath, it 

 is forced up by the hand against these gages, which perform the 

 double purpose of regulating or equalizing the round of the 

 book, and of determining its height to allow of the formation of 

 a groove of the size required. These gages are attached to sliding 

 bars, which pass through the frame on each side post, and con- 

 stitute inclined planes, raising the gages from the back of the 

 book, as they pass oft' beyond the two ends. When the book is 

 fixed in its position, and is held fast by the screws which pass 

 through the jaws, the gages are thrown back as above stated, by 

 a lever which at the same time disengages two pins or hold fasts, 

 that keep tlie jaws upright while the book is being adjusted, al- 

 lowing them, when thus free, to swing back and forth under the 

 pressure of the roller. 



"When the book is thus prepared the roller is let down upon 

 the centre of the back, which being turned by a crank, allows 

 the roller to pass down from the centre to each side, by which 

 means the grooves are formed over the edges of the jaws. 



Two levers, loaded with weights, and bearing upon the pins 

 connected with the brass boxes above mentioned, press the roller 

 hard upon the back by means of tlie weights. The whole is 

 under the control of the foot, a treadle being connected with the 

 levers by two upright connecting rods. The weights are held 

 suspended, and the roller is consequently kept in a raised po- 

 sition by a ketch which is disengaged by the foot to produce the 

 pressure. 



A cast iron frame, consisting of two upright posts and a cross 

 piece at the top, connects all the parts and holds them adjusted 



