366 Thoughts on Ray-vibrations. [1846. 



the charring of the wick is not hastened. Here, therefore, 

 there is an adjusting power, and it was found by the trials 

 made, that when the tube dipped about J an inch into the lamp- 

 glass, it left the burning of the lamp unaltered, and yet carried 

 off all the products of combustion. 



The power already referred to, of dividing a chimney into 

 separate and independent parts, and yet enabling it to act 

 perfectly as a whole, as shown in the single central chimney, 

 was easily applicable in the case of several lamps, and gave a 

 double advantage ; for it not only protected the lamps from any 

 influence of down draught, but it easily admitted of the rotation 

 of the system of gathering flues, fixed to the frame sustaining 

 the lamps and reflectors in a revolving lighthouse, and of the 

 delivery of the burnt air, &c., from its upper extremity into 

 the upper immoveable portion of the flue. This capability in 

 a revolving light is essential, for in all, the support of the frame- 

 work is of such a nature, as to require that the upper part of 

 the flue should be a fixture. 



The author explains, that it is as an officer of the Trinity 

 House, and under its instructions, that he entered into the 

 consideration of this subject ; that, as to the central chimney, 

 its action has been both proved and approved, and that all the 

 central lights are ordered to be furnished with them ; that as 

 respects the application to separate and revolving lamps, the 

 experiment has been made under the direction of the Trinity 

 House on a face of six lamps, being a full-sized copy of the 

 Tynemouth revolving light, and, so far to the satisfaction of the 

 Deputy Master and Brethren, that the plan is to be applied 

 immediately to two lighthouses which suffer most from conden- 

 sation on the glass : he believes it will be with full success. 



Thoughts on Ray -vibrations*. 



To Richard Phillips, Esq. 



DEAR SIR, At your request I will endeavour to convey to you 

 a notion of that which I ventured to say at the close of the last 

 Friday-evening Meeting, incidental to the account I gave of 

 VVheatstone's electro-magnetic chronoscope ; but from first to 



* Philosophical Magazine, 1846, vol. xxviii. p. 345. 



