i b 



Mr. F. M. Lyte on an Instrument for taking Soundings. 345 



An accurately constructed tube of gun- 

 nietal or brass, or some metal not very easily 

 corrodible by salt water, has a glass tube fitted 

 on to it on the top by a screw joint, and again 

 on the top of the glass tube is fitted a strong 

 hollow copper ball by a similar screw joint. 

 The lower tube, which we will call a, has a 

 well-turned piston fitted to it, from which 

 runs a rod which is only a trifle longer than 

 the tube a, and just enters the tube b when 

 the piston is at its lowest point. A well-made 

 spring is placed in the tube a above the piston, 

 and the tube a being narrowed at the top, so as 

 just to admit the free passage of the rod, and 

 the rod having a little button at its top, the 

 piston is kept at its lowest point by the spring, 

 except when sufficient pressure is applied from 

 below to compress the spring. The glass tube 

 has a small ring fixed in it, just so as to stick 

 at any point to which it is pushed, and the 

 button at the top of the rod serves to push 

 the ring straight, and the ring thus forms an 

 index of the degree to which the spring has 

 been compressed. The ball on the top serves 

 as a mere reservoir of air to equalize the action 

 of the apparatus as much as possible. The 

 whole of this apparatus is enclosed in a wire 

 cage for the sake of protection from blows. 

 To graduate this apparatus, I let it down in a 

 known depth of water, say ten fathoms, and 

 having observed the point to which the ring 

 in the glass tube is pushed, and having marked 

 this point off, the ball is to be unscrewed, and 

 with a small ramrod the ring is to be pushed down till it rests 

 on the top of the piston-rod. The ball being replaced, the 

 apparatus is sunk in twenty fathoms ; after a similar manner it 

 is sunk in thirty, and next in forty fathoms. This will test the 

 accuracy of the apparatus ; and the marks made on the glass 

 tube b after each trial will give a scale from which the whole 

 tube may be graduated, even to thousands of fathoms, if the 

 tube be long enough or the spring strong enough. I have been 

 induced to make this communication on account of the great 

 use which may be made of such an apparatus. 



I remain, your very obedient Servant, 



F. Maxwell Lyte. 



Phil. Mag. S. 4. Vol. 6. No. 40. Nov. 1853. 



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