US3518A - Alonzo fabkar - Google Patents

Description

FARRAB Metallic Refiecter.

Patented April 4, 1844.

N, PETERS. Phnlo'Lilwgmpher. Washingtom D. C.

j lowing description, taken inconnection with k ALONZQ FARRAR, or Bos'r-ON, MassAoHUsn r'rs.

METALLIC nnrnnoron.

Specification of Letters Patent No. 3,518, dated April 4, 1844.

To all whom it may concern: i

Beit known that I, ALoNzo FARRAR, of Boston, in the county of Suffolk and State of lvlassachusetts, have invented a new, and useful Improvement in Metallic Reflectors or Mirrors for the Purpose of Protecting their Polished Surfaces, and that the folthe accompanying drawings hereinafter referred to, formsa full and exactspecification of the same, wherein I have set forth the nature and principles of my said im-' provement by which my invention may be distinguished from others of a similar class, together with such part or combination as I CltI lIIItIHCl ClGSlI'B 1Z0 have secured to me by Letters Patent- K The reflectors or mirrors now in common use, in light-houses and on railroads are usually made of a parabolic shape, for the purpose of reflecting rays, or a beam of light in a direction parallel to its axis. They are formed of copper and have their concave surfaces plated or coated with silver, highly polished for purposes of reflection. The smoke from the lamps, andthe dust, &c., which accumulate from time to time upon the polished surfaceof a reflector tend to tarnish it considerably, and the necessary cleansing and re-polishing consequent thereon, will diminish and in time destroy the reflecting power of the same.

My improvement consists in applying a surface of flint glass, or in fact, y what may be termed a parabolic lens (when the reflector is parabolic) and when it is of any other shape, a lens made perfectly symmetrical with the reflecting surface of the mirror, to said reflecting surface, the lens or glass being fitted oppositely to, and in close contact, with, said surface.

The mechanical construction or conformas;

tion of a reflector, made with my improvement, is represented in the figures of the ac companying plate of drawings, the mirror shown being of a parabolic shape as above set forth.

Figure 1, is a front view ofthe reflector,

and Fig. 2, is a vertical section takenin the plane of the line A FigQl. y 3 y y a a, Fig. 2, is the back plate ofythe reflector, made of copper or any other suitable metal, andshaped in the usual way,

having one circular holeb, for the insertion of the lamp, and another 0 on the opposite side of the apex of the mirror for the accommodation of the chimney of the'burner. The fittings on the back of the reflectorfor hanging the same, are of the ordinary kind and need not be described;

set forth, as is also the glass lens e 6, Figs. 1, and 2. This lens is shaped as hereinbefore specified, and is fittedt o the reflecting surface of the mirror as above set forth, beingmadeof an uniform and SllfllClBIlt thickness to insure strength and durability. The lens 6 eis cemented or her,-

metically sealed to the mirror or reflector around 1ts perimeteror edge, and around the edges of the holes or perforations 7), 0

in the following manner, or in any other suitable way, the mode of cementing being no part of my invention, and being described only because it is that which I have adopted.

I first apply a sufficient" number of coats of.

gold beaterls skins around all of the aforesaid edges, to make them perfectly air tight,

and then cover or surmount the saidedges with a confining r1m f f, 9 9, gproperly grooved out or shaped as shownin section in Fig. 2. Putty or any suitable cement may then be fitted in any proper way in that part of the groove of the rims f fig a, g y,

which is not filled by the edges of the reflector and lens, so as more eifectu ally to prevent the admission of air.

By an arrangement, such I described it W111 be seen, that the polished surface of a reflector maybe always kept moved, without injury to its surface.

Having thus described my improvement I shallspecify my clalm as follows z [I olaim a The combination with a parabolic or concave reflector or mirror as ordinarily constructed, or the applying or fitting to the as that above T polished orrefiecting surface of the same, i

of a concavesurface ofglass or a concave glass lens or. meniscus made perfectlysyinmetrical with said surface, so as to be oppositely adapted to the same, all the exi 60 The silver plate (Z (Z which forms the refleeting surface is fitted in the usual way, and perforated liketlie back plate man to accommodate the lamp and chimney as above posed edges of the lens or reflector being proveinent I have hereto set my signature hermetically or otherwise sealed so as to be this tenth day of February, in the. year air tight, the Whole being constructed subeighteen hundred and forty-tour.

stantially as herein above setforth, and for ALONZO FARRAR. 5 the purpose specified. Witnesses:

In testimony that the foregoing is a true EZRA LINCOLN, Jr.,

description of my said invention and im- THOMAS LAMB.

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