22 



SCIENTIFIC NEWS. 



[July 6, 1888. 



notice, taken oTer a considerable area in Herts., Cambs., and 

 Essex, and I find the average clutch to be 4^ eggs, and the 

 average brood to be only 3! young birds ; these figures show 

 that about 30 per cent, of the eggs to be unproductive. 



From these observations, which I have carefully made, the 

 sparrow is not so prolific as it is generally supposed to be, 

 and it may be quite possible for the " British Farmer " to 

 kill them down too close, and to their present troubles they 

 may add worse enemies than the sparrow to eat their crops. 



I believe the foregoing peculiarities have no parallel. 

 Royston. Joseph P. Nunn. 



P.S. — There were not more than half the number of 

 sparrows breeding in this neighbourhood last season that 

 there were in the season of 1886, neither were the eggs of 

 last season so well coloured as those of 1886. Five per cent, 

 only of the broods contain five young birds. 



ARSENIC IN CRETONNE. 



I wish to bring to the notice of your numerous readers a 

 fact that appears to have escaped observation up to the 

 present time. I allude to arsenic poisoning by means of 

 cretonnes, imitation Indian muslins, etc. Dr. Giffard, the 

 medical officer at Coopers'-hill, has brought some cases to 

 me in which he thought he detected symptoms of arsenic 

 poisoning, and in every case the source of the poisoning was 

 traced either to a cretonne or an imitation Indian muslin that 

 had been used as a decoration by the student. As, during 

 the last twelve months, four unmistakable cases of arsenic 

 poisoning have been brought to my notice, I have recently 

 been investigating the subject. The samples upon which the 

 experiments have been performed were supplied by a local 

 tradesman. The results obtained on analysis are as follows: 

 44 samples of cretonne have been analysed, and of these 

 none were found absolutely free from arsenic, three contain 

 only the very faintest trace, and 21 contain larger traces. 

 The remaining samples all contain arsenic in poisonous 

 quantities ; in my analyses I have grouped 1 1 of them as 

 "very bad," and the other nine are bad and distinctly 

 dangerous. It may be mentioned that one of the worst 

 specimens has been examined quantitatively and yielded an 

 amount of arsenic equivalent to rather more than 195 grains 

 of white arsenic As 2 O, per square yard. As a dose of 2J 

 grains of white arsenic has been known to prove fatal, I 

 should like to point out the extreme danger that exists from 

 the indiscriminate use of these materials. It is quite a com- 

 mon occurrence to have enough of these substances in a 

 room which would contain sufficient arsenic to give one 

 hundred people a fatal dose. As far as the analyses have 

 gone at present they do not show that any one colour is 

 more poisonous than another, as, strange to say, the greens 

 and blues, that would be first suspected, have until now 

 proved purer than reds, browns, and blacks. In the case of 

 imitation Indian muslins, five samples only have been 

 analysed, but they all contained arsenic in poisonous quan- 

 tities. That such a state of affairs should be allowed in this 

 country at a time like the present seems scandalous, and I 

 would recommend no person to use any ot these fabrics for 

 decoration unless either the vendor guaranteed the absence 

 of arsenic or that they had first been analysed by some trust- 

 worthy chemist. F. E. Matthews. 



Cooper's-hill, Staines. 



Relation between the Wave-lengths of Light and 

 its Intensity. — Professor Ebert (Ciel et Terre) is examining 

 if the speed of light is in any relation to its intensity. He 

 employs interference-gratings, and shows that by this 

 method changes in the wave-lengths amounting merely to 

 the i-20o,oooth of their value, or changes in the speed of 

 light amounting merely to ± 1*5 kilometre per second, 

 may be indicated. Different sources of light were sub- 

 mitted to experiment, and it was proved that the wave- 

 lengths and the speed of light were "not changed by one 

 millionth of their value, whilst the intensity of the light 

 varies by 1 to 250. 



RECENT INVENTIONS. 



The following list has been compiled especially for the Scientific 

 News by Messrs. W. P. Thompson and Boult, Patent Agents, of 

 323, High Holborn, London, IV. C. ; Newcastle Chambers, Angel 

 Row, Nottingham; Ducie Buildings, Bank Street, Manchester ; 

 and 6, Lord Street, Liverpool. 



Telegraphs. — A type- printing telegraph has been 

 patented by Mr. G. A. Scott. This invention consists 

 essentially of a series of magnets, having their armatures 

 so arranged relatively to a flexible connection secured to 

 the type wheel, that the part of the wheel bearing any 

 required character may be turned round to the printing 

 point by opening or closing the circuit of a battery 

 through the coil of one or all of the magnets. 



Pipe. — Mr. C. J. Coventry has patented a tobacco 

 smoking pipe. The bowl of the pipe is constructed in 

 the usual manner with a hole at the bottom in line with 

 the stem. Into this hole is placed a solid metal tube, 

 having slots cut in it. When the mouthpiece is screwed on 

 to the bowl of the pipe it pushes the perforated tube 

 into the hole in the front part of the bowl, and renders 

 it air-tight. When it is necessary to let out the nicotine, 

 the stem is partially unscrewed, which thus releases the 

 perforated tube and allows the nicotine to escape. 



Knife-guard. — Mr. A. L. Mora has patented a guard 

 for use with carving forks. The guard or stop proper 

 consists of a piece turning upon centres in the fork 

 shank. The stop is made of a springy nature, so that 

 when it is raised the springing action causes the lower 

 parts of the stop to enter the recesses provided for the 

 purpose, and to be supported thereby. To release the 

 stop it is pressed against the springing action, and so the 

 lower parts leave the recesses, and the stop can be 

 turned out of its raised or effective position. 



Extinguisher. — An automatic lamp-extinguisher has 

 been patented by Mr. A. Breden. This invention relates 

 to that class in which two spring-clacks are used, which, 

 when in nominal conditions, are under the upper edge 

 of the wick-tube, but when the lamp is inclined, rise and 

 unite together above the flame, but sometimes fail to put 

 out the light. According to this invention one of these 

 spring-clacks is replaced by rigid plates, which enclose 

 the wick on three sides, the remaining clack being articu- 

 lated between the lower ends of the lateral walls of these 

 rigid plates, and penetrating between the same under the 

 action of its spring, when the extinguisher is actuated. 

 Thus the tight casing is provided, which effectually ex- 

 tinguishes the lamp. 



Type-writers. — Mr. H. A. Gruhl has patented a type- 

 writer. The invention relates to that class of type- 

 writers in which the printing mechanism is caused to 

 move above the sheet of paper to be printed upon, and 

 the object is to facilitate the alternate use of two or more 

 sets of type. This is effected in the following manner. 

 Two or more sets of type are made use of, arranged con- 

 centrically on the lower side of a segment, the pivot of 

 which can be moved in a rectangular direction, whereon 

 the letters have to appear upon the paper. Controlling 

 rows of letters, which correspond with the types at the 

 under side of the segment, but in the reverse arrange- 

 ment are attached to the upper side of the segment, and 

 appear alternately according to the position of the type- 



