III. MISCELLANEOUS. 643 



This was ceased to be employed on account of the rarity 

 of sunshine. Designed by F. Galton, Esq., F.R.S. 



2nd. A system of five collimators, fixed firmly to a wall on a 

 circular arc, arranged so as to send parallel rays across 

 the testing table at known angles. Designed and con- 

 structed by J. Cooke, and described in the Proceedings 

 of the Royal Society, vol. XVI., page 2. 



Kew Committee of the Royal Society, Kew Observatory. 



3139. Spectacles for Divers, for use in water. 



Francis Galton, F.R.S. 



When we look down into still clear water we see all objects in it with per- 

 fect distinctness, but on bending down the head with the eyes open, the 

 moment that they touch the water all distinctness of vision ceases. The 

 convex surface of the eyeball has indented the plane surface of the water with 

 a plano-concave lens, and, if we desire to restore distinctness of vision, we 

 must use convex glasses of sufficient power, when immersed in water, to 

 neutralise this effect. A double convex flint glass, each of whose surfaces has 

 a radius of about half an inch, is therefore required. By means of the glasses 

 exhibited it is possible to read the smallest type under water, with perfect 

 ease. The principle of these glasses was described in a memoir read before 

 the British Association in, 1865. 



3140. Ground Tongs for Sea Soundings; indented by 

 Francis Hopfgartner, Austrian Imperial and Royal Naval Officer 

 of the line. Lieut. Hopfgartner. 



A hole is bored lengthways through .the centre of an ordinary plummet. 

 In this hole is inserted a movable metal rail, at the lower end of which there 

 are attached two ladles or spoons, opening and closing by means of a hinge 

 or link. At the upper end there are two movable bows which are joined to 

 the ladles by small chains. If the plumb-lead is suspended to these hook-like 

 bows by means of two short auxiliary lines, the ladles are opened and the 

 apparatus is then ready to be let down into the water. On reaching the 

 ground the bows will fall back, dropping the auxiliary lines, the weight of 

 the lead presses the ladles into the ground, and by pulling up the main plumb- 

 line, which is now acting directly on the metal rail, the ladles are closed and 

 drawn into the hole of the lead so far as to be securely closed. 



3141. Ground Tongs for Sea Soundings, with dropping 

 weight ; invented by Francis Hopfgartner, Austrian Imperial and 

 Royal Naval Officer of the Line. Lieut. Hopfgartner. 



Two ladles or spoons, intended for securing specimens of the sea bottom, 

 are opened and closed like a pair of tongs by means of two levers. A peculiar 

 metal cover, in which the ladles will fit, secures the closing of the same. At 

 the upper ends of the two limbs of the tongs there are two hook-like mov- 

 able bows, on which the lead is placed, which, on the apparatus being let 

 down into the water, keeps the ladles in an open position. On reaching the 

 ground the bows will drop back, the weight (stone or a ball) will fall off, and 

 the metal cover will encase the ladles, and keep them closed while the appara- 

 tus is being pulled up. 



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