WITH THE MICROSCOPE. 31 



hardened by being heated red hot and suddenly dipped in cold water, 

 inserted into a strong handle, may be used. I generally use an 

 etching needle ; the point requires to be sharpened from time to time 

 upon a hone. But a properly pointed diamond is far better. The dark 

 parts are shaded by lines placed very close together, or cross shading 

 may be adopted, or the tint may be given by dots, as in copper-plate 

 engravings. Generally it is better to try to obtain the appearance of 

 texture by copying, as nearly as possible, the character of the tints of 

 the object itself. The thickness of the line in the impression will 

 depend upon the width of the line on the stone, without any reference 

 to the depth to which it extends into it. It is desirable to make two 

 or three narrow lines near to each other, instead of one wide one, 

 when a thick line is required. After all the lines have been scratched 

 the stone is sent to the lithographic printer, who will obtain impres- 

 sions from it. The oily material which is applied adheres to the 

 rough scratches only, and subsequently when the stone is wetted, the 

 ink only attaches itself to the oily parts. 



55. Lithographic Ink, Lithographic Stones. The ink may be 

 obtained in the fluid state, but it is better to use the solid ink, a little 

 of which is rubbed up with water when required. Lithographic 

 chalk may be obtained of different degrees of hardness, it can 

 always be made much harder by melting it and rolling it into sticks.* 

 The stones are sold by the pound. It is desirable to obtain 

 stones large enough to hold four octavo pages of drawings, as the 

 expense of working a stone of this size is a but little more than one 

 large enough to contain only a single plate. 



5G. Of representing Peculiarities of Texture. Success in draw- 

 ing microscopical specimens, depends mainly upon a careful study 

 of the different methods of shading, by which the idea of texture may 

 be given, as well as mere light and shade. It is most difficult to give 

 general directions on this matter, and much depends upon the method 

 of illustration determined upon. Various tints and textures would be 

 produced in a different manner according as the drawings are engraved 

 on copper, stone, or wood. I have no doubt that the most perfect 

 results can be obtained on steel, copper, or stone, but the expense of 

 these methods is a serious objection, and for some years past I have 

 abandoned them in favour of wood engraving which has many advan- 



* The apparatus, ink, chalk, &c., alluded to, can be obtained of Messrs. Water- 

 low, Messrs. Hughes and Kimber, Red Lion Court, Fleet Street, and most 

 lithographers. It is only due to Messrs. Harrison, of St.' Martin's Lane, that I 

 should thank them for the kindness they have always displayed in assisting me in 

 carrying out this and many other plans of producing drawings. Without the 

 important help they and their workmen have afforded me, on all occasions, my 

 efforts would probably have failed, as I had no knowledge of practical lithography. 



