164 



SCIENCE. 



[Vol. I., No. 6. 



bolt ; so that, when the current passes by B', 

 it always traverses the lamp, and, when the 

 two machines are at work together, the two 

 currents are united hy the connection between 

 the two staples. The upper staples are con- 

 nected in the same way to the apparatus in the 

 second stor}' ; and, when the bolts are raised, 

 the upper lamp is lighted. 



The regulators can thus be changed in two 

 waj's, — either by drawing the lamp at work 

 back on the rails, and quickly pushing the 

 other one in its place ; or by manipulating the 

 commutator bolt, which shifts the luminous 



A — Engine and boiltr house & — Elcctuc generator room. 

 F — Foi ge and heavy 1 cpair shop d — Shopfoi light repairs. 

 B. — Coal depot, with -water-tank underneath, c. — Water, 

 tank, v.— Vestibule. 



arc from one story to the other. Since the 

 establishment of the hghts at la I-I6ve, the 

 latter lueaus have been found superfluous, and 

 will DO longer be emploj'ed. 



Tlie light of Planier, which has just been 

 finished, is about eight nautical miles from the 

 port of Marseilles, upon a rock. It is a tower 

 sixty metres high, and eighteen metres in diame- 

 ter at the base, which rests on the rock itself. 



Fig. o gives the details of the summit of the 

 tower, and Fig. 6 those of the optical apparatus. 

 In the latter figure are shown the fixed-light 

 apparatus, and, movable around it, the drum, 



with vertical lenses. The mechanism for driv- 

 ing the latter is given in considerable detail. 



In this apparatus the changing of the regu- 

 lators is effected bj^ means of a system of two 

 pairs of rails ; but they are not placed at an 

 acute angle, as at la H6ve. One enters direct 



into the optical apparatus ; the other is placed 

 outside, and at right angles to the first. At 

 their junction is a turn-table; and, with this 

 arrangement, the manoeuvre of changing the 

 lamps takes no longer than with oblique rails. 

 The de Meritens machines, which feed the 

 regulator, are placed in a special building. 



