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366 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 ½ 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 dues, 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 immovable portion of the flue. This capability in a revolving light is essential, for in all, the support of the framework 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 Tyne mouth 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 condensation on the glass: he believes it will be with full success.

Thoughts on Ray-vibirations.

To Richard Phillips, Esq.

,—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 Wleatstone's electro-magnetic chronoscope; but from first to