Mar. 9, 1888.] 



SCIENTIFIC NEWS. 



holes are provided with screen tops to prevent the 

 emission of light. The left side of the light-box is en- 

 tirely closed, but the right side is fitted with a door for 

 the introduction of fresh carbons, etc. 



In the middle of the door is a round hole, covered with 

 dark-coloured glass for examining the light. In the 

 bottom of the light-box there is a round opening for 

 illuminating the preparation table and promoting 

 ventilation. Over this aperture there lies, supported on 

 ribs, a dark glass, which moderates the light and catches 

 the falling ashes. Between the two condensers is the 

 glass trough (S), with plane sides, filled with a saturated 

 solution of alum to arrest the heat-rays. But, lest mas- 

 sive or dark-coloured objects should be too strongly 



heated, a current of cold air is forced upon the prepara- 

 tion by means of a flexible tube coming from the bellows 

 on the foot (A). 



The arc light requires a current oi ten amperes and a 

 tension of fifty volts, and has, if thus supplied, a 1,200 

 candle-power. This strength of light suffices for a 

 magnifying power of 1,000 diameters. But for using oil 

 immersions it can be intensified by means of the achro- 

 matic condenser, devised by Professor Abbe, and manu- 

 factured by Zeiss, of Jena. In this manner an illumina- 

 tion is obtained equal to that of 2,500 normal candles. 



At the distance of five and a-half yards from the screen 

 the contractile vacuoles, and the granular current in living 

 amoebas, as well as the ciliary movement in infusoria, can 

 be seen. 



We need scarcely say that this apparatus will be of 



the highest value to professors of every department of 

 the organic sciences. 



AN ANIMATED TRINKET. 



A SKILFUL mechanician, saysZ« Nature, has recently 

 submitted to our examination an animated trinket 

 which is a wonder of ingenuity. It is a neck-tie pin in 

 the form of a bird's head. The wearer asks some one to 

 look at his scarf-pin, and at the same moment the bird 

 opens its beak and utters a short but very expressive 

 warbling. The engraving represents the mechanism. 

 The pin (fig. i) has attached to its lower part a caout- 

 chouc pipe terminating in a ball, which is kept in the 

 pocket. On pressing this ball with the hand, air 

 is forced up the tube and acts on the mechanism in the 

 head of the bird. The sections 2 and -i show the 



arrangement. The air passing along one of the branches 

 of a U tube circulates through a little whistle, and in the 

 other branch it raises a small piston fitted with a counter- 

 poise which opens the beak of the bird. 



Adhesive Gum for Labels. — The following mixture is 

 given by M. Eliel for a strongly adhesive gum, which will 

 really make paper or parchment paper stick to any surface 

 on which it may be applied, such as wood, glass, stone, or 

 metal of any kind. It is made thus ; — 



Gum acacia .. .. .. .. 120 parts 



,, tragacanth . . . . . . 30 „ 



Glycerine . . . . . . . . . . 120 ,, 



Thymol . . . . , . . . . , 24 ,, 



(or) Australian eucalyptus oil . . 3:^ „ 



Water, sufficient to make up to 1,000 parts 



