3 14 Mr. F. M. Lyte on an Instrument for taking Soundinys. 



of the aether, can with no propriety be called modulatory, the 

 word unda implying the motion of a mass. It is desirable that 

 two theories, perfectly distinct in their principles and wholly 

 incompatible with each other, should also be distinguished in 

 name, and I would therefore call the latter the oscillatory theory 

 of light, this term having been recently made use of by an advo- 

 cate of that theory. I venture to add here one consideration, 

 tending to show that the establishment of the theory of light on 

 hydrodynaraical principles may have an extensive bearing on the 

 progress of theoretical physics. Light, considered apart from 

 the sensation so called, is simply a force, which may be placed 

 in the same rank as heat, electricity, magnetism, &c. Let it be 

 proved that this force is due to the transverse vibrations of a 

 continuous elastic medium, and the inference can hardly be 

 resisted that heat is due to the direct vibrations of the same 

 medium. Thus these two forces would be resolved into pres- 

 sures, obeying laws which may be investigated on mathematical 

 principles, and it might reasonably be presumed that other forces 

 admit of like explanation. Whatever may be the truth of this 

 induction, 1 am prepared to maintain that many phenomena of 

 light may be explained by the motions and pressures of a con- 

 tinuous elastic medium, and to this object I propose, as I find 

 leisure, to apply some of the hydrodynamical theorems which 

 have been discussed in various communications to this Journal. 



Cambridge Observatory, 

 October 6, 1853. 



LI I. On an Instrument for takiny Soundings. 

 By F. Maxwell Lyte, Esq. 



To the Editors of the Philosophical Mayazine and Journal. 



Florian, Torquay, 

 Gentlemen, September 19. 



AS I see, from what Dr. Scoresby has been saying before the 

 Association at Hull, there seems to be some difficulty 

 about obtaining a correct sounding in places where the currents 

 are strong and flow in different directions at the different points 

 of depth, causing the line to assume different curves in its descent; 

 and when it comes to be measured over, after the weight has 

 reached the bottom and been hauled up again, the measurement 

 gives no approximate idea of the real depth, — now it is plain 

 that this mensuration of the depth of water might be as well 

 made by estimating its vertical pressure, as, in measuring the 

 height of mountains, we measure the barometrical pressure of 

 the air ; and so I would propose to do it by an instrument con- 

 structed as follows : — 



