TELEGRAPHIC PORTRAITS.

Star (Christchurch), Issue 5256, 11 May 1895, Page 2

TELEGRAPHIC PORTRAITS.

(St James's Budget.)

The inestimable cervices rendered to science and art by photography are now among the commonplaces of the day. The sensitive eye of the camera, immeasurably transcending both in delicacy and power the visual organ of man, is constantly discerning and registering for permanent reference facts, especially in the domain of astronomy, beyond the reach of human viaion, even when aided by the most powerful of telescopes. Bui; if photography has deserved thus well in the loftier region of science, her services are none the less remarkable in the more homejly paths of everyday life. The camera has beon used to catch by stealth and permanently record the features of criminals in the Tory commieaion of their crimes and thua to aasiac the work of justice. And now, with the aid of electricity, this nsefnl handmaid of the arts ia likely to render further aid in bringing law-breakers to book, for it has beenfoundpoesibleto transmit photographs by telegraph. The merit of discovering this remarkable process ia attributed to a German inventor, Mr N. S. Ametutz, of Cleveland. His method, which ia simple, appears to be an adaptation of the well-known proceaa by which such objoctß, say, as gunatocka aro now made, by means of drills which, through tbe instrumentality of an ingenious mechanical arrangement, are made to follow the contour of a revolving model, an exaot copy of which thoy reproduce .from a piece of wood subjected to their operation while it revolves at precisely the same speed as the model. Wood-carvings are produced in a very similar fashion. For the telegraphic transmission of photographs there J are placed at the despatching and receiving ofiioea corresponding cylindrical rollers similar to those employed in the phonograph, the equal and parallel movement of which ia ensured by a mechanism of clockwork. In contact with the cylinder at the despatching office is a, pencil, the point of which, when tho cylinder is made to revolve, travereea it in spiral lines from end to end. The pencil ia so adjuated that the atrength of the current varies according to the resistance offered to the pencil-point by auy variations on the Burface of the cylinder. So long as the surface is even there is no variation in the current; but should ib precont any inequalities the strength of tbo current varies with its risings and fallings, while the penoil still continues to describe ita cloae spiral lines. Thia varying current ia, by proper electrical means, transmitted to tho receiving station, whero in its turn it bo influences a penoil in contact with the wax covered surface of the receiving cylinder as to cause it to impress upon it

grooves varying in depth according to the changing strength of the current. In order that a photograph may be thus transmitted, it haa first, by the ordinary process of photo-printing, to be converted into a gelatine relief, whioh ia placed npon the transmitting cylinder, whioh ia then eet in motion. Following, aooording to the proceaa described, the risinge and fallinga of tbia reliof, the pencil of the receiving cylinder roproduoea in olose opiral lines a sort of elementary copy of iU