The Optical Magic Lantern Journal (July 1890)

The Optical Magic Lantern Journal and Photographio Enlarger, Is then marked off on the first scale by turning the ring A until its pointer is at 12. then rotated until its pointer reaches the figure on the scale of the first ring denoting the sensitiveness of the plate to be used, which may be 3. The third pointer S is then turned to the figure on the second ring corresponding to the particular colour or character of the subject. which for an average landscape is 1. Vhis having been done, the fourth ring D is made to point ina similar way to the stop used, say I'S. when the point E will be found to give the duration of exposure (four seconds) according to the condition of the light, the make of plate, nature of subject, and the stop employed. The second ring P is: | when at the door. Tables giving the most suitable number for each : make of plate, &c., are supplied with each instrument. The meter, which is only 2in. long, is neat and Strong. It is constructed on principles, and reflects great credit upon its inventor, and can be relied upon as a correct means of calculating exposures. es AN interesting treatise on Aluminium, its uses and alloys, has been received from the Alliance Aluminium Company, Limited, 7, Great Winchester-street, E.C. Varied applications are suggested for the use of this metal, which 1s of beautiful colour and lustre, is very light, strong, and hard, will not oxidize, and can be easily worked. Amongst the different articles enumerated in which this metal can be better employed than others are photographic apparatus and magic lanterns. aoe A NEW catalogue has lately been prepared by F. E. Becker and Co., of Hatton Wall, London, E.C. In it is to be found a comprehensive list of photographic goods stocked by this firm. To enumerate the various novelties would make a long list, so we leave our readers to judge for themselves, as they can obtain the catalogue on application. The cover is of striking appearance. ete Mr. A. W. Scott, of Weston-super-Mare, has sent us one of his new Saturators. This is well-finished in brass, and is the same in general detail as that first introduced by him. An illustration will be found in his advertisement on page iv. 10: Correspondence. CAMERA OBSCURA. (To the Editor.] S1r,—Under certain conditions, the effect mentioned by Mr. Davis can be produced; but as he does not give any particulars of the nature of his camera, it is somewhat difcult to advise him how to alter his; but perhaps he can obtain the information he desires from these few lines :— The building should be conical in shape, the lens fixed in one side of a box surmounted on top, which must be capable of being rotated. In this box isa mirror, inclined at an angle of gsdegs. ‘This will cause the rays of light passing through the lens to fall upon the table; the focussing may be done by raising or lowering the table. In order to see a person standing at the doorway (z.e., looking down, as it were, upon the person's head) a mirror must be placed above the door, immediately in front of the lens and in such a position that a perpendicular line from it will be slightly outside of the entrance. The image will thus be reflected by the outside mirror through the lens, thence by the reflector behind the lens upon the table. Thus effect at best is not anything great, and it may be the case, as it is upwards of 30 years since Mr. Davis saw this effect, that ‘distance (of time) has lent enchantment to the view.’ — Yours, Xc., ORSCURA. Thirsk, Yorks. — * To the Editar.) S1r,— Double reflection is the only way by which the effect of the representation of the man at the door of camera ob-scura can be produced, and then only if the light is very ‘ good; but the image will only be that of the person end on strictly scientific : Of course, the further the person is away the less the mirror must be inclined, and the more the figure of the individual will appear.— Yours, &c., Kensington, W. Jas. S. RoBertson, BLOCKING OUT STATUARY, &c. [To the Editor.) Dear Str,—Will you, through the medium of your useful little journal, inform me what is the best pigment for blocking out statuary 2? The same pigment would be useful for coating glasses for slides to be written upon, as I find the writing comes out brighter and clearer when written upon a prepared black slide than when written in black upon a ground or mat surface slide. I should lke to get a compound dense enough to prevent light going through it, and yet fluid enough to coat a glass in the same way as one would use collodion or varnish. {he surface would be more even than if put on witha brush. — Yours faithfully, J. W. SPENCER. Trowbridge, June 14, 18go. (Try mastic or copal varnish, with which has been well: mixed up some lamp-black, until when spread upon glass it is quite opaque. It may be thinned with a little turpentine if necessary. —ED. ] PERFORATED LIMES. [ Lo the Editor] Str,—During my experience I have had considerable: trouble with the cracking of limes, and I have been trying a few experiments to prevent this. I have, after some troulle, managed to bore a series of small holes through the lime. parallel to that in which the pin goes. The lime which I have thus prepared has been subjected to several trials, and: in my hands it answers well.—Yours, &c., Birmingham, June 6, 1890. HERBERT G. WALLIS. 102 Society Meetings. ENFIELD CAMERA CLUb. — A meeting to consider the: desirability of forming a camera club for Enfield and the: neighbourhood has been held at the Lancaster Coffee Tavern, . Baker-street, Enfield. Eventually it was resolved to forma society to be called the Enfield Camera Club. An entrance fee of 2s. 6d. ancl an annual subscription of 5s. were fixed, and it was agreed to admit ladies and professional photo sraphers to membership. Mr. D. G. Pinkney was aske.l to: accept the presidency, and Mr. Dudin the post of honorary secretary pro tem. STOCKPORT PHOTOGRAPHIC SOCtETY.—The first annual: meeting was held on the rrth ult., Mr. W. Banks in the chair. The report showed a membership roll of 40 members, with a cash balance in hand and an amount of £8 3s. towards the optical lantern. The following were elected asofficers for the year :—President, Mr. Thomas Kay, J.P ; , vice-presidents, Mr. Thos. Hidderley and Mr. W. Banks ;.