CONSTRUCTION OF THE MICROSCOPE. 81 



being fixed (if necessary) by a screw-clip. The coarse adjustment is 

 made by sliding the body through the outer tube which carries the ob- 

 ject; and the fine adjustment by sliding the eye-tube in or out. The 

 object, if transparent, is illuminated either by holding up the Microscope 

 to a window or lamp, from which the rays may pass directly through it, 

 or by directing it towards a mirror laid on the table at such an angle as 

 to reflect light from either of these sources: if opaque, it is allowed to 

 receive direct light through an aperture in the outer tube. The extreme 

 simplicity and portability of this instrument (which when closed is only 

 six inches long) constitutes its special recommendation. With due care 

 even high powers may be use, the eye-piece adjustment giving the power 

 of very exact focussing. Hence this Pocket Microscope may be conve- 

 niently applied to the purposes of Clinical observation (the examination 

 of Urinary Deposits, Blood, Sputa, etc.), either in hospital or in private 

 practice; whilst it may also be advantageously used by the Field Natural- 

 ist in examining specimens of Water for Animalcules, Protophytes, etc. 



Era. 53. 



Dr. Beale's Demonstrating Microscope. 



77. Dr. Beetle's Demonstrating Microscope. The same instrument 

 may be used for the purposes of Class-demonstration, by attaching 

 its outer tube on a wooden support to a horizontal board, which also 

 carries a small lamp attached to it in the required position (Fig. 53). 

 The object having been fixed in its place, and the coarse adjustment 

 made by sliding the body in the outer tube, these parts may then be im- 

 movably secured, nothing being left movable except the eye-tube, by 

 sliding which in or out the fine adjustment may be effected. Thus the 

 whole apparatus may be passed from hand to hand with the greatest facil- 

 ity, and without any probability of disarrangement; and every observer 

 may readily ' focus' for himself, without any risk of injuring the object. 1 



78. Baker's Travelling Microscope. An instrument has been devised 

 by Mr. Moginie, which is but little inferior in portability to the Pocket 

 Microscope of Prof. Beale, and has some advantages over it. The body 

 (Fig. 54) slides in a tube which is attached to a stem that carries at its 

 end a small Stage and Mirror. The stem itself contains a fine adjustment 

 that is worked by a milled-head at its summit; and near to this is attached 

 by pivot- joint a pair of legs, which, when opened-out, form with the stem 

 a firm tripod support. The coarse adjustment having been made by 

 sliding the body through the tube which grasps it, the fine adjustment is 



1 The price of Dr. Beale's Clinical Microscope, as made by Mr. Collins, without 

 Objectives, is 1 11s. 6d. That of the same instrument fitted up as a Demonstrat- 

 ing Microscope, is 3 3s. Mr. Collins also makes another Class and Demonstra- 

 tion Microscope, or a pattern of Dr. Lawson's for 3 10s., without Objectives. 

 6 



