lKfU90niAl ANIMALCt?T,Bg. 101 



the attention of my workmen to the suhjcct, and gave them, fi'om 

 time to time, such iiiibnnation, as, with tlieir skill and perseverance, 

 might advance them in tliis branch of art, and I believe, up to the 

 present time, the only successful artists in this coimtry are those who 

 have been in my employ. 



In cases where an achi'omatic microscope camiot be prociired, 

 recourse should be had to single lenses or doublets, for the ordinary 

 compound, however well constructed, cannot be depended upon. 



With respect to the cost of an effective microscope, with a mode- 

 rate equipment of apparatus, such for example as the one described 

 in the 6th chapter of the Microscopic Illustrations, with its recent 

 improvements, the price would now be from 20 to 50 guineas. Aft 

 there are a great many persons who require only a plain, soimd 

 instrument, of more moderate cost, I have deemed it expedient to 

 take this also into consideration, and, after much application and 

 repeated experiments, have at length produced one, in eveiy way 

 suitable to the case. Such is my "miniature aclrromatic microscope.' 

 It may be stated that nine-tenths of the observations recorded in thia 

 work may be repeated and tested by this microscope. On comparing 

 the above instruments with that used by Elu'enberg, there is no doubt 

 that, in point of mechanical eonsti'uction, they are greatly superior, 

 whilst the optical part is equal to any ■n'ith wliich his researches have 

 been made. 



My experience induces me to recommend to all who wish to study 

 this subject, two microscopes — the one a small vertical one with a 

 little achi-omatic body. The construction which I prefer, is similar 

 to that drawn and described in the Microscojjic Cabinet, page 243, 

 The stage is cuxailar and the body is about four inches long, it is 

 usually known as the "Miniatiu'e Aclu'omatic Microscope," its piece,, 

 with an object glass of one-seventh of an inch focus, is five guineas. 

 This instrument I find preferable, in the first examination of an 

 object, to a larger and more expensive microscope, while in travelling, 

 its portability is a strong recommendation. Its defects are, that you 

 cannot use a low magnifier with the achromatic body, but this is of 

 little moment, as a few single or doublet magnifiers will always com- 

 pensate for it. As many persons may think such an instrument a 

 mere toy, I can assiu'e them, that with the addition of a powerful 



