DRAWING MATERIALS. 67 



143. Drawing Materials. These are required in all kinds of 

 Natural History work, and may be conveniently mentioned here. 

 In addition to the writing pencil, there should be at least two for 

 drawing, the one of medium, and the other of considerable hard- 

 ness. All pencils should be " hexagonal" to prevent rolling, or 

 else provided with a hexagonal rubber eraser. For the neatest 

 work, however, it is well to use a separate eraser with a brush for 

 removing the crumbs from the paper. (See Readers and Writers 

 Economy Co., A.) It is so often desirable to double the size of 

 objects that the "duplicating dividers" are more useful in place 

 of or in addition to the ordinary dividers. India ink is used for 

 some drawings and for writing upon parchment (see 149). 



144. Drills. A laboratory should have afoot latlie like, for 

 example, the one figured by Goodnow & Wightman, A, 73. But 

 most of the holes required in bone, wood or metal, may be made 

 by a small u Hand drill," like, for example, that figured on p. 14 

 of the same Catalogue. 



145. Forceps, Coarse and Fine Figs. 18, 20. Both pairs 

 are absolutely necessary, and the fine ones should be curved. With 

 nearly all forceps, the spring is too strong ; it should be only suffi- 

 cient to separate the blades when the pressure of the fingers is 

 relaxed. If the dealers will not supply forceps with the proper 

 spring, the desired change may be effected with a file or grindstone. 

 The "Coxeter" style of coarse forceps is to be preferred. Those 

 represented in Fig. 18, have the blades excavated so as to be lighter 

 than those formerly made. 



146. Nippers Fig. 10, 11. These are the " diagonal side 



cutting nippers or pliers" of the dealers in hardware. The obli- 



i quity of the blades to the handles gives them great advantages over 



! either the "side cutting" pliers, or the "cross cutting," which are 



shown in Fig. 10, left figure. Seven sizes are made, ranging from 



10-20 cm. (4-8 in.) in length. Those of 10 and 15 cm. are best 



! adapted to anatomical work upon small animals. The larger of 



these will cut any of the bones of cats less than two years old, but 



the larger bones of older individuals may require the saw. For 



i some purposes the points should be quite sharp, and may be made 



so with a file or upon a grindstone. 



A. "Pointed nippers with oblique jaws" are mentioned by Newton (B, 22, 174), but 

 I they do not appear to be in general use by anatomists. The nippers have been used in 

 ( anatomical work, especially for the removal of the brain, by the senior author since 1871, 

 and are mentioned in his paper, 11 9 158. 



