Improvements in bi-focal lenses and their manufacture, and in apparatus to be employed in the said manufacture / [Malcolm Bentzon].

  • Bentzon, Malcolm.
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: Improvements in bi-focal lenses and their manufacture, and in apparatus to be employed in the said manufacture / [Malcolm Bentzon]. Source: Wellcome Collection.

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    5 10 15 20 25 30 35 40 A.D.1004 Date of Application, 29th Dec., 1904 Complete Specification Left, 30th Oct., 1905—Accepted, 29th Jan,, 1906 PROVISIONAL SPECIFICATION. “ Improvements in Bi-focal Lenses and their Manufacture, and in Apparatus to be employed in the said Manufacture >> r We, Malcolm Bentzon, of 188, Strand, in the County of London, carrying on business as an Engineer, under the style of Malcolm Bentzon & Co., and Alfred Henry Emerson Junior, of 26 Eyre Street Hill, Clerkenwell in the County of London, Manufacturing Optician, do hereby declare the nature of this invention to be as follows: — Our invention relates to solid bi-focal lenses, more especially intended for spectacles and eyeglasses, that is, lenses made from one piece oi glass, pebble, or the like, with two foci, and our said invention consists in improvements in the lenses themselves and in their manufacture, and in apparatus to be used in such manufacture. The solid bi-focal lenses, of the kind known as “ solid down- curve bi-foeals ”, hitherto produced, or proposed, have a ridge between the two foci which ridge has a bad appearance and prevents the lenses from being cleaned with the same ease as ordinary lenses, but hitherto no practical means have, so far as we are aware, been devised to successfully produce two different foci optically correct on one piece of glass, or the like, without a ridge, and it is the object of one part of our invention to provide practical means for the production of such lenses, whereby we obtain optically correct solid down- curve bi-focal lenses wherein the curvatures of the two foci of the lens join each, other exactly on the same plane, so that the dividing line is practically invisible, and so that there is no obstruction to the sight and no disfigurement to the wearer, and so also that the lens can be cleaned as easily as an ordinary lens. The lens may be made of any known, or suitable, kind of glass, pebble, or the like, capable of being used for the purpose, but we will refer to it as glass. Hitherto it has been the general practice to rough grind and smooth grind lenses for spectacles and eyeglasses by hand, the polishing only being effected by machinery, but, by the means according to our invention, we are able to perform all three operations by machinery and to operate upon the two curva¬ tures of one lens, or of two’, or more, lenses, simultaneously. . The apparatus which we have devised for this purpose consists of a frame¬ work supporting bearings in which is mounted a lower spindle carrying a disc, or lens holder. Perpendicular to the face of the lens holder are upper spindles, supported in bearings in carriers, preferably each consisting of an arm hinged, or pivotted, at one end to a moveable block adjusted by a_ screw, or lever, and at the other end moveable, in a radial, vertical, and horizontal direction, so that the tool carried by each spindle can be set exactly above the glass, or glasses, to be operated upon/ The said upper spindles each carries at the end nearest the lens holder a detachable hollow and spherical grinding, or po is tool attached in such a manner that it will automatically take up and keep its proper position upon the surface of the glass being operated upon,, the con¬ nection of the spindle with the tool being effected by a universal joint pre- hPrice 8r/.]