So far as the candle-power of any light is concerned, the method of determining this factor, varying according to the calculating methods adopted, is somewhat misleading. So far as Great Britain is concerned, the practice of setting out the candle-power of any light in the official list has been abandoned, the authorities merely stating that such and such a light is of great power. The United States and Canada, on the other hand, indicate the approximate candle-power. [Illustration: _By courtesy of Messrs. Chance Bros. & Co., Ltd._ FIXED APPARATUS OF THE FOURTH ORDER FOR SARAWAK. The focal distance is 250 millimetres, and the diameter of lantern inside glazing 6 feet 7¾ inches.] By combining and arranging the integral parts of the optical apparatus, the lighthouse engineer is able to accomplish many astonishing results. Thus, while the various types generally follow accepted broad lines, coinciding with the order which they represent, here and there some very striking divergences are made. The Bell Rock light is perhaps the most interesting example in this direction. It was designed by Messrs. D. and T. Stevenson, and built by Messrs. Chance Brothers and Co. The light is alternating, the colours being white and red. Externally the optical apparatus appears to be bizarre, yet it is one of the most perfect which has ever been installed. In its design and construction almost all the known lighthouse optical elements are incorporated, including the equiangular refractor, the reflecting prism, the double-reflecting prism, and the dioptric mirror. Another noteworthy fact is that, by an exceedingly ingenious arrangement, the absorption of the rays by the glass used in producing the red flashes is neutralized to such a vast degree that the white and red flashes are of equal intensity.