148 KECORD OF CURRENT RESEARCHES RELATING TO 



just Below the funnel. The advantage of this over the ordinary- 

 dipping tube is that by first pressing the iudiarubber with the finger 

 (when the orifice is closed with the thumb), and thus forcing out air, 

 small quantities of water together with minute objects will, when the 

 finger is withdrawn, be taken up out of shallow vessels, such as watch- 

 glasses, &c. In addition there is perfect control over the water, and 

 it can be expelled by the mere touch of the finger on the indiarubber ; 

 whereas in the old form of tube the water has to be blown out with 

 the mouth, entailing the removal of the eye from the Microscope, 

 which sometimes is very inconvenient. 



Mr. Bolton in writing to us says that he wishes to add that by 

 the aid of this tube a larger quantity of water can be drawn out of a 

 small bottle or tube than could be accomplished with the old form ; 

 in fact, it can be used as a kind of syringe, but for this purpose he 

 now prefers a small tube with a capillary point to which an india- 

 rubber teat is attached. 



Wills' Compressorium. — In the same paper Mr. Bolton describes 

 a simple form of compressorium that we do not remember having 

 seen previously described. Two pieces of thin glass are cemented to 

 a glass slip in the shape of the letter L, but with the two strokes of 

 the letter about equal in length, and another thinner and longer one 

 is fixed longitudinally, thus L . The L serves to retain in posi- 

 tion a square slip of cover-glass placed, not on the L, but inside it ; 

 the horizontal piece, which should be ground to a bevel on its top 

 edge before fixing it, serves to carry a fine needle, the point of which 

 is inserted beneath the edge of the cover-glass. This point being 

 tapered, it is easy to increase or diminish the thickness of a film of 

 water carried between the cover and the slip by pushing the needle 

 further in or out, and so to form a cheap and efiective compressorium. 

 Those who try it will be surprised at its eflBciency. 



Graham Compressorium. — This consists of a brass plate somewhat 

 larger than the ordinary slide, but about the same thickness, with a 

 central hole ^ inch in diameter, slightly recessed on the upper side so 

 as to admit of a |^-inch circle of thin glass being cemented in. Near 

 one end a stout screwed pillar is riveted inside a small brass cylinder, 

 containing a spiral spring. A brass cap fits over the cylinder, having 

 at its lower end an arm carrying the upper (|-inch) circle of thin 

 glass. A milled head working on the fixed screw presses down the 

 arm while the spiral spring raises it, when the milled head is turned 

 the reverse way. The glasses are perfectly parallel, and can be 

 turned quite clear of each other for cleaning, and if broken can be 

 very readily replaced. The thinness of the bottom plate allows the 

 paraboloid or achromatic condenser to be used. 



Botterill's Live Trough. — The advantages claimed for this form 

 of trough, which is shown in Fig. 13, are the facilities it afibrds (1) for 

 being cleaned, (2) for replacement of broken glass, (3) for arranging 

 the objects in the best position for examination, (4) for reversal, and, 

 lastly, the minor one that it will stand upright without support. 



It consists of two brass plates, which can be separated and screwed 

 together again at pleasure, and hold between them two plates of glass, 



