Progress in Science.

New Zealand Graphic, Volume XLIV, Issue 8, 23 February 1910, Page 45

Progress in Science.

Some Photographic Diversions.

By

GUSTAVE MICHAUD,

Costa Rica State College.

gyr V ACHROMATIC LENSES, such / I as the common spectacle lens, H are sometimes used by phot'ographers who aim at the production of artistic effects. The breadth of interpretation observed in pictures made •with those defective lenses is a result' of the suppression of small details. The impression left by the masses of light and shade is that which is felt before erayon work or oil painting, or before the landscape itself when we enjoy it; that' is, When we are not paying particular attention to some minute part of it. Such artistic effects may be easily obtained with any objective, through the use of two implements, made once for alt by the photographer himself, implements for which the names of "crayon screen” and “ oil painting screen” would be appropriate.

The crayon screen breaks the uniform photographic shades into numberless and irregular dots, lines, or spots, so that viewed through a magnifying glass, they look very much like those produced by crayon drawn over rough paper. The screen may be made by copying with the camera and without reduction, a Sayer of crayon uniformly laid over coarse drawing piper. Better results are obtained by copying, wi** - considerable reduction, some irregular design, made of spots, lines, and dots, on a printed fabric such as is found in every dry goods store. Herewith is the reproduction, in natural size, of the fabric used for the making of the screen with which the crayon effect in the accompanying engraving was obtained. If the screen is a film, it should be placed in the printing frame, between negative and paper. If it is a plate, it is most conveniently used in the negative holder, over the plate, and will then give, after a rather long exposure, a erayon effect negative. Most holders will take and hold in place two plates of ordinary thickness.

Photographs which look as if they were copies of artistic oil paintings may be made with any good negative and the help of the oil painting screen. This is merely a negative made from any framed oil painting, in which a piece of coarse cloth is substituted for the painting.

A print is made with this negative. It is not' toned or fixed and, with penknife and rule, the cloth central part is cut out from the print. This operation gives Vo upper masks, one of the cloth and \ le of the frame. Printing is made first kzith the negative of the landscape or portrait with the peripheral frame mask laid on the sensitised paper, the holder being placed about normally to the rays of the full sunlight, without ground glass but with a glass plate interposed between negative and paper. The dis-

tance thus introduced destroys the small details, leaving only masses of light and shade. The oil painting screen is then used in lieu of the negative. It is placed in direct contact' with the paper and frame mask until the canvas effect is clearly seen on the print. Last, the central mask is substituted for the frame mask, and a third printing gives the frame. The oil painting effect is the result of the contrast between the small details of the canvas and the seemingly broad technique of the picture over it.

Safeguarding Railway Crossing!. It is customary in Europe to place a Setting under high-tension lines at railroads and important street crossings. As a further protection at .such points an inventor has recently devised a safety suspension in which the line is divided into three parts at the crossings and supported on three insulators, any one of which will bear the entire weight of the line at that point in case the others be fused or broken. The German Post Office Department has approved of this system, and permits its use at crossings. «><?><?> Earthquake Alarm—lmportant Invention. Working on the theory that earthquakes are preceded by an electro-mag-netic disturbance, an Italian scientist has devised an instrument which gives warning that an earthquake is about to occur a few minutes before the disturbance is felt. With this instrument the inventor, Padre Maccione, received warning of two earthquake shocks that occurred about ten miles from his laboratory four minutes before tire earthquakes affectel

the seismograph. The instrument is connected to a clock, and is so arranged as to record the time elapsing between the arrival of the electro magnetic wave and the seismic waves. Improving the X Rays. One of the drawbacks of using Rontgen rays to photograph living subjects has been the fact that a time exposure was

required. In order to overcome this difficulty a German inventor has devised an induction coil which produces one sudden and very intense spark, and this makes it possible to take an instantaneous radiogram. The effect is produced by using a fuse in place of the interrupter in the primary circuit, and this is melted when the proper intensity of the current is reached, thus very suddenly breaking tho circuit and producing an intense discharge. The exposure is from 1-50 to 1-20 of a second; and as it is a simple matter to replace the fuse a large number of exposures can be made in the course of an hour. The fuse consists of & small copper or silver wire. <s><?><?> A Ceratopsian Skeleton. The American Museum of Natural History has acquired about two-thirds of * skeleton of a ceratopsian, a newly-dis-covered species of which the triceratops or dinosaur is a member. The skeleton’s size is about the same as the triceratops, which it resembles generally. The discovery of this remarkable preliistorio animal was made by Barnum Brown of the museum staff, who has just returned with an expedition from Montana. Th« Laramie formation in which the skeleton was found is estimated at 3.000.000 years. This species of dinosaur was a herb eater and walked on four feet. Its measurements, if it is the same as a triceratops, should be about twentyithree feet long, and about seven feet wide.