Small Round Holes Research Articles

Radio Screening of Sparking Plugs

AS early as 1894, in a paper on the subject of electrical radiation read at the Royal Institution, Sir Oliver Lodge explained the steps that it was necessary to take to screen electrical radiation. He pointed out that lor effective screening every part of the oscillating circuit must be completely enclosed in metal casing, and all the metal enclosures well connected together. He also explained that while small round holes in the casing did not matter, anything in the nature of a slot or chink, or the smallest “live” part of the circuit projecting through the casing, would allow the radiation to pass. The ignition system of a petrol engine generates an oscillating discharge, sending out electrical radiation, and to prevent this radiation interfering with a neighbouring radio receiver it is necessary to enclose the whole ignition circuit—magneto, cables and sparking plugs—in metal casing.

A SIMPLE AND INEXPENSIVE DEVICE TO PREVENT THE CONTAMINATION OF STERILE SOLUTIONS

Sterile solutions are often put into carefully sterilized bottles, closed by sterile stoppers and then set away. By the time the solutions are to be used dust has collected on the lips of the bottles and in pouring out the contents the germs are washed off and the solutions are no longer sterile. Wiping the top of the bottle, at best, removes only part of the germs and drops the rest of them directly into the bottle. Then the stopper is laid down on some unsterile surface and, loaded with microorganisms, is returned to the bottle. To obviate this I have devised a simple inexpensive device, so simple, in fact, that I hesitate to present it. From a piece of heavy rubber sheeting (that from a hotwater bottle answers best) cut a round piece, of such size that when placed over the mouth of the bottle the edges project somewhat. Then cut a small round hole in the center, of such size that the rubber

ON THE PREVIOUS STAGES OF PTINIDÆ AND ALLIED GROUPS

A small round box of bamboo (8 by 6 inches) was bought nine years ago in Hong Kong, China, and brought home to Boston. It was placed on a little shelf on the wall, and used for Turkish tobacco. The box was lined inside with a perfectly closing box made of East Indian block-tin, about a millimetre thick. I examined the box January, 1885, and found it hollowed throughout like a sieve, and containing between the tin box and the bamboo cover a large number of dead and living beetles and two living larvæ. The tin box had four small round holes apparently cut through by the insects. The beetles represented two species, one, a little larger, only two specimens, all the others belonging to the second specres.

Societies and Academies

LONDONEntomological Society, October 4,—Sir Sidney Smith Saunders, C.M.G., vice-president, in the chair.—M. Alfred Preudhomme de Borre, secretary of the Belgian Entomological Society, was elected a foreign member.—Mr. Bond exhibited varieties of Hepialus humuh and Epunda lunulenta, and also specimens of the new Tortrix (Sericoris irrinuana), all taken near Loch Laggan by Mr. N. Cooke.—Mr. Forbes exhibited a weevil (evidently not indigenous to Britain) taken alive among some orchids at Highgate. Mr. Pascoe pronounced it to be a species of Cholus, a South American genus, for which he proposed the name of C. Forbesii,—Mr. W. Cole exhibited numerous bred specimens of Eunomos angularia, showing differences in coloration according as the larvæ had been fed on oak, hawthorn, lime, or lilac.—Mr. Enock exhibited microscopic slides containing some beautiful preparations of minute species of Hymenop-tera.—Mr. Frederick Smith communicated “Descriptions of new species of Cryptoceridze belonging to the genera Cryptocerus, Meranoplus, and Cataulacus,” accompanied by figures of the several species. The author gave some interesting particulars relative to the habits of these insects, especially of Meranoplus intrudns, which constructs its formicariurn in the thorns of a species of Acacia. These thorns were some 4 or 5 inches in length, and at a distance of about half an inch from the pointed end, a small round hole was made for ingress and egress to and from the nest. The thorns contained a kind of spongy pith in which the channels and chambers of the nest were constructed. —A catalogue of the British Hemiptera (Heteroptera and Homoptera) compiled by Messrs. J. W. Douglas and John Scott, published by the Society, was on the table.