122 '. Thirty-fifth Report ok the State Museum 



graduated thumb- screw the line on which the specimen is to be cut is 

 brought opposite to the edge of the disc. The outer end of the lever 

 is then taken in the left hand of the operator and brought forward 

 toward the disc and the cutting begun, the force of the hand modify- 

 ing the degree of pressure and rate of cutting. When a specimen 

 is placed in the vise jaws, and several slices or sections are desired, 

 the arm can be lowered or raised by the graduated screw, shown at 

 FF., on the side of the vertical standard. In this way any required 

 number of slices can be cut from the same specimen, or] the whole 

 specimen cut into sections as may be required. This is shown in the 

 figure of the specimen attached to the lever. When a series of slices 

 have been cut to the depth required, the arm may be turned a quarter 

 revolution, by loosening a screw at the junction of the lever and 

 sliding socket, and the slices all cut through, leaving the residue of 

 the specimen still remaining in the vise. 



This process is perfectly adapted to all strong and solid specimens ; 

 but specimens required for cutting are not always in that condition, 

 and to provide for such as are not firm enough to endure the pressure, 

 a small disc, with ball and socket joint, has been devised, and the speci- 

 men is cemented to this disc. The socket is closed by a hinge and 

 presents a square block of metal which is placed in the disc jaws ; the 

 disc is adapted to the position required and firmly clasped, and thus 

 held while the specimen is being cut. 



For the cutting of large specimens, when the diameter is greater 

 than the semi-diameter of the disc, another adaptation has been devised 

 by which the object is perfectly accomplished. 



The machinery used in this work for the Museum has gradually 

 come into its preseut condition only after patient trial and experi- 

 ment; new parts being invented as the necessity for them became 

 apparent. 



The calcareous fossils are cut by a horizontal disc of tin, which 

 moves at the rate of five hundred revolutions per minute; and is fed 

 with emery and water. The disc which is used to cut silicious rocks, 

 such as flint, hornstone, etc., is made of soft copper "seasoned" with 

 diamond dust, and runs in a trough of oil at about one hundred revo- 

 lutions per minute. The varions attachments for holding the speci- 

 mens firmly in any required position are all from original designs. 



The following illustrations will explain the descriptions given above : 

 Plate 2, fig. 1. — A A. Perpendicular cylindrical steel rod supported 



between two centers, K K, allowing a rotary motion without departing 



from the perpendicular position. 



B B. Horizontal square steel rod or arm, with one end turned 



cylindrical, |[fitting in socket, which slides upon rod A A, which 



