i8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Feb., 1904. 



point of view of practical application, as in air an abundant 

 production of nitrous vapors is observed ; whereas in mixtures 

 of carbonic gas and nitrogen both nitrous vapours and carbon 

 monoxide are produced ; with a mixture of l)enzine and nitrogen 

 vapours, cyanogen and hydrogen will be obtained. On account 

 of the importance of the problem in practice. Kowalski and 

 Mosciki have especially dealt with the production of nitric 

 vapours and hence nitric acid. They were able to obtain up to 

 44 grams of nitric acid per kw. hour, it appearing from their 

 calculations that the price of one kg. of calcium nitrate would 

 not be upwards of I'jd. 



De Kowalslii next describes some experiments made on 

 electric discharges on the surface of insulating bodies. As one 

 side of the insulating plate is covered with a conductive layer 

 while discharges are being produced on the other, sparks very 

 much longer than without a conductive layer are obtained. 

 Photographs presented by the author show the sparks to 

 follow accurately the way drawn by conductive laver on the 

 side of the plate opposite to the discharge, it being thus pos- 

 sible to obtain sparks of a triangular, square, zigzag, &c., 

 shape. The author finally points out the analogies shown by 

 the discharges with those produced in the atmosphere during 

 thunderstorms. 



On some Novel Phenomena in connec- 

 tion with N-Rays. 



Professor Blondlot actively continues his investigations of 

 N-rays. and in a paper recently read before the French 

 Academy of Sciences we note some interesting facts. The 

 author has some time ago observed that sources of light would, 

 under the action of N-rays, show an increase in brilliancy. 

 Xow Blondlot thought it interesting to test whether the same 

 phenomenon takes place in the case of a body reflecting the 

 light from an external source being employed instead of an 

 illuminant proper. The following experiment was accordingly 

 made: A ribbon of white paper, 15 mm. in length and z miri. 

 in breadth, was fixed vertically to an iron wire support ; the 

 room being darkened, the paper ribbon would be feebly illumi- 

 nated by projecting on the same, laterally, a beam 'of light 

 given off from a small plane enclosed in a box where a vertical 

 slit was provided. The X-rays from an Auer burner, traversing 

 a rectangular slit in front of the above slit, would strike the 

 paper ribbon. Xow, if the rays were intercepted bv inter- 

 posing either the hand or a 'lead plate, the small paper 

 rectangle would be darkened and its outline lose in distinct- 

 ness; as soon as the screen was taken away again both the 

 brilliancy and distinctness would reappear, this giving evidence 

 of the light diffused by the paper ribbon being increased under 

 the action of X-rays. 



Xow. the difiusion of light is a complex phenomenon, where 

 regular reflection plays the part of an elementarv fact. The 

 author therefore thought of investigating whether the reflection 

 of light is also modified under the action of X-rays. To this 

 effect, a polished knitting needle of steel was placed vertically 

 in the position formerly occupied by the paper ribbon ; in a 

 box completely closed but for a vertical slit at the height of an 

 .Auer lamp (shut by a screen of transparent paper), a flame was 

 placed so as to illuminate the slit. When adjusting conve- 

 niently the eye in the slit, the image of the latter formed bv 

 reflection on thi steel cylinder was distinctly seen ; while the 

 reflecting surface .as struck by X-rays, when the action of 

 the ray proved to strengthen the image. Similar results were 

 obtained, replacing the needle either by a plain bronze mirror 

 or a polished quartz surface. All these actions of X-rays 

 retjuire an appreciable time both to be produced and to dis- 

 appear. On the other hand, no action of X-rays on refracted 

 light could be observed, though various experiments in this 

 direction were undertaken under many diff'erent conditions. 



As the capacity of seizing small \ariations in candle power 

 is rather different for different persons, these phenomena are 

 nearly at the limit of perceptibilitv to some persons, who. only 

 after a certain practice, will be able to seize them regularly 

 and to observe them safely, whereas others will at once, and 

 without the least difticulty, note the strengthening effect of N- 

 rays on the candle power of a small illuminant. Xow, as the 

 author has recently observed the same phenomena, with con- 

 siderably increased intensity, when replacing the- .Auer burner 

 by a Xcrnst lamp, the.se phenomena may now be produced 

 with such intensity as to be visible to anybody. 



The Printing Telegraph 



The Berlin Teletyping Central Station. 



Telephones, rendering only words as they are spoken, 

 are frequently insufficient for business purposes ; in ad- 

 dition to a correct transmission of a communication, 

 there will in many cases be necessary an acknowledgment 

 in writing of this transmission. On the other hand, 

 there is the liability of telephonic conversation to be 

 overheard by a third person, and finally the person rung 

 up on the telephone may happen to be absent, when his 

 return will have to be waited for, and much time be lost. 

 In order to afiord an efficient means of communication in 

 all these and many other cases, a new public printing tele- 

 graph service was installed in Berlin on Oct. ist, when 

 the " Ferndrucker Centrale " was opened to public service. 



The telegraph, as constructed by the Siemens and 

 Halske Company, is a type-printing telegraph similar to 

 the well-known Hughes type printer and the Baudot 

 telegraph. The main distinctive feature from former 

 apparatus is, however, the fact that the latter moving 

 freely, the simultaneous working of the instruments 

 established on the same line had to be obtained by the 

 skill of the operator, whereas the operation of the new 

 apparatus is as simple as that of an ordinary typewriter. 

 The apparatus, in fact, is nothing else than a teletype- 

 writer, any letters, figures, or signs of punctuation being 

 printed by pressing down a key corresponding with the 

 signal in question. There are two circles of signs on the 

 periphery of the type wheel, one comprising the letters 

 and the other the figures and signs of punctuation. A 

 .<^hift key serves to adjust the type-wheel either for letters 

 or figures. Both sets of apparatus, connected by a line, 

 may be used either as sender or as receiver, without any 

 special preparation being necessary, as soon as a special 

 white key is struck ; the apparatus in question is in fact 

 made to serve as sender, and all will be ready for use. 

 The printing takes place simultaneously in both the 

 transmitting and recei\-ing apparatus, no matter whether 

 there is or is not somebody operating the receiving ap- 

 paratus. In the case of the owner of the apparatus 

 being absent, lie will read the telegram printed on the 

 paper ribbon on his return. The new telegraph, giving 

 two identical records of the same telegram in the sending 

 and receiving apparatus respectively, will place at the 

 disposal of the transmitter an evidence of the correctness 

 of his communication, so as to exclude any possibility of 

 misunderstanding. 



The advantages afforded by the printing telegraph, as 

 compared both with telephone and present telegraph 

 system, will be self-evident. Like the telephone, the 

 new telegraph may serve for a direct communication 

 between any two persons o\er any distances, but for its 

 being free from any possibility of hearing mistakes or 

 other misunderstanding, in virtue of the double simul- 

 taneous reproduction in printing of each communication. 

 At the same time, there is, as above stated, no danger 

 of a third person overhearing the communications. This 

 is therefore the only means of communication enabling 

 despatches to be kept strictly private. 



A central station with arrangements and working 

 methods similar to those of central telephone stations has 

 been opened in 28, Zimmerstrasse, Berlin, serving in the 

 first place to secure mutual communication between all 

 the subscribers connected to the Berlin printing telegraph 

 net. The central station is fitted with a switchboard 

 comprising indicators and cathices for one hundred sub- 



