each series successively decreasing in diameter.
The lantern is supported on a cylinder of boiler-iron resting on a platform at the top of the columns.
Lighthouse at Trinity shoals.
The following is a list of the electric lights in England and France, with the dates at which they were erected: Dungeness, January, 1862; Cape La Heve, France, South Light, December, 1863, North Light, November, 1866; Cape Grisnez, France, February, 1869; Souter Point, England, January, 1871; South Foreland, England, with two lights, January, 1872, in the first place in 1858 – 60 by Professor Holmes, and afterward England took the lead in this matter of the adaptation of electric illumination to lighthouse purposes.
The Bishop rock light, Scilly Islands, the old Cassiterides of Herodotus, 145 feet high, cost £ 36,559. In the British Isles there are 357 shore lights and 47 floating lights.
The French have 224 shore lights.
The average annual expense in England of a shore light is £ 500; of a
be imprisoned in the chamber, to adapt the instrument to work in an atmosphere of any temperature, with a bubble of a normal size.
Mr. Wurdemann was the first to hermetically seal a tube containing the chamber, previous to which time it was closed by glass plates, bladder, and glue.
The most curious and delicate apparatus for leveling, in dividing and graduating instruments, and adapted for many other purposes, is the contact-level invented by Repsold, a celebrated instrument-maker of Hamburg.
It is described on page 612, and room cannot be spared for duplicate descriptions.
2. (Mining.) a. A horizontal gallery or passage in a mine.
The workings at different depths are said to be at the different levels,—the 50 or 60 fathom level, and so on.
b. An adit or drift forming a drain for water.
A level which opens to the surface at the side of a valley is called a day-level, and forms a means of natural drainage without pumping.
A drowned or blind level