HARD WI CKE ' S S CIENCE- G SSIP. 



167 



bowling-green from Cunliffe Road, and having a 

 circular orifice inside, the birds were able to get in 

 and out without trouble. The postman, finding what 

 was going on, left his letters in another place, and 

 the birds were left undisturbed except by the opening 

 and closing of the door, which after a time ceased to 

 concern them much. Four eggs were laid, on which 

 the mother had sat for a fortnight, when some ruth- 

 less person stole them, much to the regret of the 

 members of the club, who had felt quite proud of 

 their feathered guests. The nest has now also dis- 

 appeared, so that the eviction is complete. — Harry 

 B. Booth. 



Spontaneous Combustion. — Professor Vivian 

 Lewes, of the Royal Naval College, who has given 

 special attention to the matter, recently drew renewed 

 attention to the subject of spontaneous combustion in 

 coal cargoes in a paper read before the Society of 

 Arts. The conclusion which Professor Lewes has 

 come to, and the recommendations which he has 

 made to obviate the loss of life and property arising 

 from this cause, are engaging attention, and may 

 probably be the subject of legislation. The Royal 

 Commission appointed in 1S75 to inquire into this 

 subject came to the conclusion that the presence of 

 iron pyrites among coal was the primary, and the 

 absorption of oxygen by the coal a subsidiary cause 

 of spontaneous combustion. Professor Lewes exactly 

 reverses the position of these causes, and fixes on the 

 absorption of oxygen by coal as the principal and 

 almost only cause of combustion. To bring about a 

 condition of possible combustion it is necessary that 

 sufficient oxygen should be absorbed. Coal will 

 absorb about twice its volume of oxygen. A ton of 

 coals will stow in a space of about 42 cubic feet, of 

 which space the coal itself occupies only about 30 

 cubic feet. Hence about 300 cubic feet of air are 

 required to completely saturate a ton of coal with 

 oxygen ; and Professor Lewes maintains that with 

 the ventilation that can be applied in a large cargo 

 hold, the amount of air will only, roughly speaking, 

 be about sufficient to place the coal in its most 

 dangerous condition, -and have no effect in cooling 

 the mass or carrying off the dangerous gases. The 

 contributory causes of combustion Professor Lewes 

 finds to be the increase in the weight of coals carried 

 in one hold, usually accompanied by fine subdivision 

 due to the method of loading ; the pressure of mois- 

 ture, which increases the action of the absorbed 

 oxygen ; ventilation, and the presence of external 

 causes of heating, such as the proximity of a boiler or 

 steam pipe to a bulk -head against which the coal is 

 stowed. 



Wild Duck's Xest. — A wild duck, which recently 

 built its nest in a tree near the mansion, in Wilder- 

 mere Park, Sevenoaks, forty feet above the ground, 

 has hatched her young and returned to the lake. The 

 young 'ducks, eight in number, followed, running 

 along the branches and alighting on the ground from 

 the nest without the slightest injury. This was 

 witnessed by Mr. Burroughs and two or three mem- 

 bers of the household, and a few days ago our repre- 

 sentative saw the mother sitting on the eggs in the 

 tree. — The Kent and Sussex Courier, May 2"jlh, 1892. 



Electricity guards many of the treasures of the 

 Metropolitan Museum of Art in New York. In the 

 room containing the Moses Lazarus collection of 

 miniatures, painted porcelain, and other rich and 

 valuable objects of art, there are %vires running 

 underneath the lid of each case. If anybody tried 

 to lift the cover or disturb it in any way, a bell 



would ring in General Di Cesnola's office, and also 

 give warning on the ground floor by ringing a big 

 gong. There is a similar arrangement in use with 

 other valuable cases. 



A wind apparatus for generating electricity and 

 charging secondary batteries has been patented in 

 Canada by Mr. James M. Mitchell, of Atlanta, Ga. 

 The device consists of a dynamo mounted on high 

 tubular standard or staging and driven by a wind 

 wheel, the current generated by this dynamo is 

 stored in a secondary battery ready for use, the 

 generating circuit is automatically opened when the 

 secondary battery is charged to its full capacity. 

 The current generated at different times and in 

 different quantities, owing to the variable force of 

 the wind, is safely stored and may be used for every 

 purpose. 



NOTICES TO CORRESPONDENTS. 



To Correspondents and Exchangers. — As we now 

 publish Science-Gossip earlier than formerly, we cannot un- 

 dertake to insert in the following number any communications 

 which reach us later than the 8th of the previous month. 



To Anonymous Querists.— We must adhere to our rule of 

 not noticing queries which do not bea-r the writers' names. 



To Dealers and Others. — We are always glad to treat 

 dealers in natural history objects on the same fair and general 

 ground as amateurs, in so far as the ** exchanges" offered are 

 fair exchanges. But it is evident that, when their offers are 

 simply Disguised Advertisements, for the purpose of evading 

 the cost of advertising, an advantage is taken of our gratuitous 

 insertion of "exchanges," which cannot be tolerated. 



We request that all exchanges may be signed with name (or 

 initials) and full address at the end. 



Special Note. — There is a tendency on the part of some 

 exchangers to send more than one per month. We only allow 

 this in the case of writers of papers. 



To our Recent Exchangers.— We are willing to be helpful 

 to our genuine naturalists, but we cannot further allow dis- 

 guised Exchanges like those which frequently come to us 

 to appear unless as advertisements. 



W. W. C. (Wolverhampton).— The specimen sent us is the 

 Chimes {Allium schoinoprasum). 



T. H. — It is the Silvenveed [Potentiila argentea), not a 

 common plant. 



R. S. T. — The Saw-fly {Sirex giganteus). See a good figure 

 of it in " Playtime Naturalist." 



W. J. S. — The New Zealand caterpillar with the clubbed 

 fungoid growth at the tail was figured and described under 

 the common name of the "Vegetable Caterpillar," in Science- 

 Gossip for 1865. It has long been a popular wonder, and 

 thousands of them have been sent over to England by colonists 

 to their natural history-loving friends. 



F. J. R. (Clifton). — Many thanks for the specimens of 

 abnormal flowers of foxglove. No other order has its members 

 so likely to "go wrong" than the Scrophulariaceai, and no 

 other order has such a wide range of. external floral structure. 

 The foxglove is especially guilty in this respect. The peculiar 

 form of aberration in the specimen sent is described by Dr. 

 Masters in his notable and rare book, "Vegetable Tera- 

 tology," under the name of synanthy— that is, several flowers 

 growing together, the number of which can be ascertained by 

 counting the stamens. The synanthic flower measured 4$ 

 inches across — an unusual size. 



J. E. W.— The limitation you suggest as to the price of the 

 book you require rather ties one's hands. The best and 

 cheapest book on minute organisms is Dr. M. C. Cooke's 

 "PondiLife" (2$. 6d., published by the S.P.C.K.). Another 

 capital and more advanced, is Professor Jeffry Parker's " Bell's 

 Manual of Biology" (Macmillan & Co., 10s. 6d.). Claus' 

 work (translated and edited by Professor Sedgewick) runs to 

 more money still. 



Illustrations. — We should feel obliged if contributors of 

 illustrated papers would kindly send their sketches separately, 

 instead of sketching or inserting them in the text of their MSS. 

 There would then be no danger of misplacement. 



MiSS S. — The plant is Salsify {Tragopogon po?-rifoHum). 



