126 



SCIENTIFIC NEV^^S. 



[Aug. 1st, 1 8 



of working the search lights at some distance from the 

 generating source. In one case the projector was fitted on 

 some ramparts ashore, and connected with the Bellerophott's 

 electrical plant by means of an armoured cable. A steam- 

 boat was then detailed to endeavour to reach the man-of- 

 war without being perceived, but the search lights fixed on 

 shore, and directed from the Bcllerophoii proved so effective, 

 that this feat was rendered impossible, and, in case of actual 

 warfare, the steamboat [would have exposed herself to a 

 raking fire from the machine-guns. Other trials tended to 

 show that if a ship could be defended by the electric light 

 in such a manner that the beams surrounded her, it would 

 be, practically speaking, impossible for any craft, however 

 small, to cross those beams without discovery. In such a 

 case the position of the ship would not be so apparent, as 

 when the projectors are fitted on board. 



Rainfall in Paris. — In the Annuaire de la Socie'te 

 Mete'orologique de France is an article by M. Herve-Mangon 

 on the distribution of rainfall and its duration in Paris, 

 based on observations taken during the years 1860-1870. 

 These observations were made with Herve-iVIangon's pluvio- 

 scope, and show that rain falls on an average 19 hours a 

 month. The month with the shortest duration of rain was 

 August, which had only i2| hours, while March had 26 

 hours, and October and November had a little more 

 than 22 hours each. An examination of the hours of the 

 rainfall during the night and during the day shows that on 

 an average there are fewer hours of rain during the night 

 than during the day. The longest interval without rain 

 was 26 days, from September nth to October 6th, 1865. 

 The greatest number of consecutive days of rain was 18, 

 from October 3rd to 20th, 1867. The month of March had, 

 on an average, the greatest number of rainy days, viz., 2f2, 

 and the month of June the least, viz., i3'i. The months 

 of greatest and least amount of rainfall do not correspond 

 with these months, the maximum being 2'2i in. in Septem- 

 ber, and the minimum I'oo in. in February. 



Ozone from Pure Oxygen. — At a recent meeting of the 

 Chemical Society a paper was read on the above subject, by 

 W. A. Shenstone and J. Tudor Cundall. The authors de- 

 scribed an apparatus in which oxygen had been prepared and 

 stored without the possibility of air gaining admittance. So 

 far as it was possible to determine the purity of the gas by 

 tests, it would appear certain that it had contained at most 

 only ^ of nitrogen. The oxygen had been collected and 

 sealed up in glass tubes containing phosphoric oxide, in contact 

 with which it had been kept for periods ranging from eight 

 weeks to eight months. Subsequently it had been submitted 

 to.the action of electricity, and the ozone produced had been 

 measured. In one experiment, made at 10 deg. C, no less 

 than 117 per cent, of the oxygen taken was converted into 

 ozone. This was a very considerably higher proportion 

 than had been obtained either by Berodie or by the authors 

 from ordinary oxygen when similar means of electrification 

 were employed, but not so high as was obtained by Andrews 

 and Tait. They, however, worked in a different way, and 

 the exact value of their results was uncertain inconsequence 

 of the tendency of the sulphuric acid used in their gauges to 

 absorb ozone. 



A Safeguard against Insects. — Many people do not know 

 how easily they can protect themselves and their children 

 against the bites of gnats and other insects. Weak carbolic 

 acid sponged on the skin and hair, and in some cases on the 

 clothing, will drive away the whole tribe. A great many 

 children, and not a few adults, are tormented throughout 

 the whole summer by minute enemies. We know persons 



who are afraid of picnics, and even of their own gardens, on 

 this account. Clothing is an imperfect protection, for we 

 have seen a child whose foot and ankle had been stung 

 through the stocking so seriously that for days she could 

 not wear a leather shoe. All this can be averted, according 

 to our experience, and that we believe of many others, by 

 carbolic acid judiciously used. The safest plan is to keep a 

 saturated solution of the acid. The solution cannot contain 

 more than 6 or 7 per cent., and it may be added to 

 water until the latter smells stronglJ^ This may readily, 

 and with perfect safetj', be applied with a sponge. We 

 have no doubt that horses and cattle could be protected in 

 the same way from the flies, which sometimes nearly mad- 

 den them, and it even seems possible that that terrible 

 scourge, the African Tsetse-flj', might be kept off in the 

 same manner. — Lancet. 



Pita. — According to a report of Consul Burchard, of 

 Ruatan, in Honduras, the pita plant has never been culti- 

 vated, but grows wild in patches on the borders of rivers 

 and lagoons. The stalks of the plant contain the fibre of 

 commerce, and grow sometimes to a height of twelve feet. 

 The Indians scrape off the hard skin of the stalk with a 

 bamboo knife, and thus obtain the fibres which form the 

 heart of the stalk. Another plan is to steep the stalks in 

 water until the skin decomposes ; but this is said to injure 

 the fibre somewhat. In recent years machines have been 

 devised to decorticate the fibre, but these have all been 

 failures, owing to the fact that no machine has yet been 

 invented capable of operating on a profitable scale. In 

 Honduras the pita or " silk-grass " fibre is used chiefly for 

 thread, nets, fish-line, and cordage. Samples of the fibre 

 sent to the United States and to Europe have been manu- 

 factured into lace, handkerchiefs, ribbons and wigs. It is 

 held to be a substitute for silk or linen ; and if proper 

 machinery were forthcoming, the produce of the wild pita 

 fields of Honduras might be used in commerce. Consul 

 Burchard indeed expresses the opinion that the fibre is 

 destined to become a very important element in the future 

 commerce and industry of the country where it is grown. — 

 Scientific American. 



Instantaneous Photography. — A new pocket camera, 

 which is being brought out under the name of Stirn's patent, 

 is just now creating considerable attention in scientific 

 circles. The instrument is designed for use by amateurs, 

 and consists of a shallow metal box 5I in. diam., which can 

 be suspended from the neck like a field-glass. Within the 

 box is a sensitised dry plate, which can be revolved from a 

 central knob. The objective is a lens contained in a tube of 

 I in. diam., placed on the front face of the box near the 

 rim, and does not require to be adjusted for distance. The 

 apparatus is specially valuable for taking photographs 

 secretly, as it can be worn under the coat with only the lens 

 projecting through a button-hole. On the inside of the 

 objective is a slide which can be momentarily opened by 

 pulling a string. We have seen some of the photographs 

 obtained, both in the original size and enlarged twelve to 

 fifteen times. They v^'ere exceedingly sharp and well 

 defined. After an impression is taken the sensitised plate is 

 turned through a sixth of a revolution by the knob above 

 mentioned, a pointer indicating the exact position of the 

 plate, which can thus receive six distinct impressions. The 

 apparatus, inclusive of six plates, costs only 30s., and owing 

 to this low price it will probably come into extended use. — 

 Industries. 



Origin of Alpine Lakes,— At a recent meeting of the 

 Royal Society of Edinburgh, Prof. Geikie read a paper by 

 Prof. Sacco, of the University of Turin, on " The Origin of 



