WITH THE MICROSCOPE. 13 



has much improved and simplified that adjustment by the use 

 of a circular disc with two eccentric slots, which entirely super- 

 sedes the rack and pinion. The shallow eye-piece, or erector, 

 is made to slide in the eye-piece tube for the purpose of varying 

 the distance between the eye-lens and the prism placed over it, 

 according to the power of the objective in use. 



In this new binocular we have a modification of the plan first 

 adopted by M. Nachet, which promises, however, to be far more 

 successful than that was. Mr. Ladd has undertaken the manufac- 

 ture of this form of binocular apparatus in England. 



18. Travelling Microscopes. Mr. Waringtoris Arra?igcment. 

 For travelling, and especially for sea-side work, it will be convenient to 

 be provided with a microscope which can be packed in a smaller 

 compass than the instruments already described. Mr. Warington, 

 some time since, designed a very simple microscope for travelling 

 purposes. The stand consists of two flat pieces of oak, fitted at right 

 angles to each other by means of pegs. The stage is inserted into 

 the longer one, to the top of which the body of the microscope is 

 adapted by means of a clamp. The horizontal bar carrying the body 

 can be moved backwards and forwards through a tube arranged to 

 receive it. This instrument can be placed in an upright or inclined 

 position, and by means of the clamp the body can be attached to a 

 table, so that living objects in upright glasses can be subjected to 

 examination. In its present form, however, the instrument is not so 

 steady as could be wished. Several improved forms of instrument 

 arranged according to the same principle have been suggested. 



19. Travelling, Dissecting, and Vivarium Microscope. Another 

 simple form of travelling microscope is described by me in the fourth 

 volume of the Transactions of the Microscopical Society, page 13. 

 This instrument was made entirely of tubes, and was very steady. 

 It could be used as a microscope for dissecting, for looking at objects 

 in a vivarium, and for all ordinary purposes. Focussing was effected 

 very rapidly by means of a knee lever, which was kindly made for 

 me by Mr. Becker, instead of a screw. The arrangement has, how- 

 ever, been superseded by cheaper instruments. 



Mr. Highley has suggested a very cheap form of travelling micro- 

 scope which is also strong and useful. This is described in the Micro- 

 scopical Journal, vol. iv, page 278. A very ingenious little micro- 

 scope, which packs in a small leather case, has more recently been 

 introduced by Mr. Baker, of Holborn. The body of the last two 

 instruments can be readily adapted to the tube carrying the stage of 

 the microscope next to be described. Mr. King, Naturalist, of the 

 Portland Road, has devised a most convenient microscope for 



