106 ANNUAL OF SCIENTIFIC DISCOVERY. 



to the world, and their conclusions hare served for the formation of a 

 system for lighthouse illumination, approximating to perfection. Leg- 

 islation, too, has taken a prominent part in this important branch of 

 the public service in Europe. In 1825, the French government 

 adopted definitely the French system on the coasts of France, and 

 took, as the basis of their future lighthouse establishment, the pro- 

 gramme proposed by the Board organized for that purpose, at the 

 head of which was Admiral Rossel, of the French navy. About this 

 time the subject, which Sir David Brewster had foreshadowed in 

 1811, was revived in England and Scotland, through Col. Colby and 

 Mr. Stevenson, the engineer of the Northern lights, (and the distin- 

 guished architect of the Bell Rock tower ;) however, no important 

 step was taken on the English side of the Channel, to introduce the 

 Fresnel apparatus, until after a most careful and rigid examination, 

 and until after trials of comparative usefulness and economy with that 

 and the reflector apparatus. Although the Fresnel lens has met with 

 much favor in England, and has been gradually getting into use, until 

 nearly one-half of the sea coast lights have been changed since 1837, 

 still Scotland has introduced a larger number in proportion to extent 

 of coast, than the Trinity Board. Notwithstanding these improve- 

 ments in the lights of Great Britain, the subject was again taken up 

 by the House of Commons in 1845, and since then a large number of 

 lens apparatus have been introduced both in Great Britain and in the 

 colonies, and the rape-seed oil, on account of its superiority and 

 economy, has been substituted for the best sperm oil, in most of the 

 lighthouses of the kingdom. While improvements in illuminating 

 apparatus, and construction, ventilation, combustibles, c., have made 

 rapid progress in lighthouse engineering in Europe, hardly any 

 attempt has been made in this country to improve the lights, and no 

 efficient protection is now afforded to the immense foreign and domes- 

 tic commerce, which is now daily risked upon our dangerous and ill- 

 lighted coasts. 



TO PREVENT WOOD FROM WARPING. 



FRANCOIS TACIIET, of Paris, has taken out a patent for the fol- 

 lowing method of preparing wood, to prevent it from warping or 

 shrinking. The ordinary method of doing this is to employ two or 

 more thin pieces, which are united together with the grain cross-wise, 

 by means of glue or liquid cement, but this only partially answers its 

 intended purpose, as glue, or cement, applied in a liquid state, is 

 always liable to be affected by a moist atmosphere, and the expansion 

 produced thereby, and the subsequent unequal contraction in drying, 

 causes a certain amount of warping. Now the object of the patentee 

 is to unite pieces of wood together, so as to render them independent 

 of atmospheric influences, and this he effects by employing the cement 

 in a dry and powdered state, and applying heat to the exterior of the 

 pieces of wood to be united, so as to effect the melting of the cement 

 by transmission. The cement which the patentee employs is gum lac, 



