NATURAL PHILOSOPHY. 165 



line from the drum on which it is coiled, so that no more can run 

 out. This appai-atus is applical)le also when the lead is kejjt hano-- 

 inof down at a certain distance from the ship, for the purpose of 

 indicating^the presence of rocks or reefs, or that the water has be- 

 come shallow, so as to give timely notice of approaching dano-er. 

 — Scientific American. 



LIGHTING OF THE CAPITOL DOME. 



The efforts of Mr. Samuel Gardiner, of New York, in this en- 

 terprise have been crowned with triumpiiant success. For two 

 years and a half tlie arrangements have Ijeen quietl}' pei-fectino-, 

 and on the evening of the 2od of January, 18(36, the dome was 

 illuminated from three circles of burners, invisible from the floor, 

 and containing 1100 jets, from 6 to 12 inches apart, bringing out 

 in splendid relief the picture executed by Mr. Brumidi on the 

 ceiling of the inner dome, at a height of 180 feet from the floor of 

 the rotunda. 



The means for operating the battery, turning on and off the 

 gas, and lighting each tier of burners, are brought within a space 

 of two feet square in a passage-way within a few feet of the 

 floor of the rotunda, and consists of a silvei'-mounted dial-plate 

 with keys, eleven in number, one in the centre, by which the 

 jDrimary connection is made, and the required amount of bat- 

 tery brought into oj^eration, the others being for the gas and 

 lighting connections of the respective tiers. Tlaese tiers, it may 

 be here mentioned, are three in number at present; the first, 

 containing 300 burners, at the lower cornice, 45 feet from the 

 floor ; the second, of 325 burners, at a cornice 80 feet from the 

 floor; the third tier, 425 burners, 165 feet from the floor, sur- 

 rounding the balustrade, and near the margin of the picture on 

 the ceiling. 



The flrst and second series of burners are entirely inaceessilile, 

 all are invisible from any part of the floor, and every possible 

 manipulation is executed at the dial-plate on the floor by the ex- 

 ertion of a few ounces pressure on tlie ajipropriate key, the gas 

 stop-cock to each tier being operated by an electro-magnetic en- 

 gine in its vicinity, which receives its imjiulse from the battery, 

 the central heart of the concei'n, communicating light, heat, and 

 force, under the guidance of the brain which directs the current at 

 will through the five miles of wire. This lieart of the apparatus, 

 whose impulses are thus directed, is housed in and fully occupies 

 an elliptical room 45 by 36 feet, and consists of 200 jars, arranged 

 on tables in concentric series, eacli jar being 13 inches in diame- 

 ter, 14 inches deep, and so arranged as to he thrown on or oft" in 

 sections of 20, by the key on the before-named dial-plate in a 

 passage remote from the battery. A vernier on the dial-plate, in 

 connection witli a pointer on the central key, indicates the extent 

 of the battery which is brouglit into ojjeration by the revolution of 

 the key. Openings in the dial expose dark and light segments 

 of the wheels on the gas keys, so as to indicate the shut or open 

 positions of the gas stop-cocks at the tiers 45, 80, 165, and the 



