398 



SCIENTIFIC NEWS. 



[Oct. 12, 1888. 



CORRESPONDENCE. 



The Editor does not hold himself responsible for opinions expressed 

 by his correspondents , nor can he take notice of anonymous com- 

 munications. All letters must be accompanied by the name and 

 address of the writer, not necessarily for publication, but as a 

 guarantee of good faith. 



EXTINCT BRITISH BUTTERFLIES. 



Your interesting article on this subject (Scientific News, 

 vol. ii., pp. 124 and 160) raises some questions to which I 

 must beg to call attention. Our climate is admittedly less 

 favourable to butterflies (and indeed to many other insects) 

 than is that of Continental districts under similar latitudes. 

 But such as it is, it has not, to our knowledge, undergone 

 any changes within historical times. Now, if the lack of 

 sunshine be a leading factor in the extirpation of, e.g , 

 Papilio podalirius and P. machaon, how, it may be asked, 

 did these species ever establish themselves in Britain at all ? 



Drainage must, of course, tell against the existence of 

 species which feed upon fen vegetation. But this is cer- 

 tainly not the case with P. podalirius and machaon. The 

 caterpillar of the former feeds upon sloes, plum, apple, and 

 pear trees, and upon oaks. Machaon feeds upon the leaves 

 of carrots, which are certainly more abundant than they 

 were formerly. Further, on the Continent machaon is not a 

 fen insect. 



I must beg to express doubts concerning the following pas- 

 sage : " In our British climate thistles and kindred plants 

 die early in the autumn, and before the larvae can feed on 

 them the chilly nights have withered the food plants." So 

 far as I remember, the autumn frosts in northern and central 

 France, Germany, etc., set in quite as early as with us, and 

 the thistles will therefore be cut off quite as early. 



The chief causes of the decrease or disappearance of the 

 larger and more striking British butterflies are, I submit, the 

 "British mania," to which you have referred from time to time, 

 and the "ravages of the picture-makers," which you mention 

 on p. 174. It is just possible that some of your readers may not 

 know what is here meant by the expression " picture- 

 makers." These people obtain by any means a quantity of 

 butterflies, aud arrange them in a glass case, not according 

 to their structural affinities, but in concentric circles, in 

 squares, triangles, crosses, or other patterns. The case is 

 then hung up on the wall as a decoration. The extent to 

 which this freak is indulged in is perfectly alarming. I have 

 seen such cases form a prominent feature in exhibitions got 

 up by country societies ; and on one occasion, when stopping 

 at Leeds, I saw an announcement that a collection of 50,000 

 beautiful insects was being exhibited in theRoundhay Park, 

 and that the owner was willing to sell. On going there I 

 found several rooms lined with these "pictures," in which 

 more butterflies had been used up than a hundred genuine 

 entomologists would have sacrificed in a life-time. To such 

 follies, more than to climate, drainage and cultivation,! think 

 that the decrease of our finer butterflies must be traced. 

 F. E. S. 



THE MULTIPLICATION OF SPARROWS. 



A correspondent in your issue of July 6th concludes, from 

 certain observations which he has made, that " the sparrow 

 is not so prolific as it is generally supposed to be." I 

 should like to ask how does he, then, account for the fact 

 that in most districts the sparrow is more common not only 

 than any other bird, but often than all other species put 

 together ? I do not think that killing down, or even, were it 

 possible, the extirpation of this marauder, would be injurious 

 to the farmer and gardener, since scope would thus be given 

 for the multiplication of the swallow and other true insecti- 

 vorous birds which the sparrow persecutes and drives away. 



As to the food of this bird, Mr. S. A. Forbes, writing in 

 the American Naturalist Tor 1881, gives the following decisive 

 evidence (p. 393) : " I add a few notes on the food of twenty- 

 five sparrows shot in and around Aurora, 111., in the years 

 1879 and 1880. At a time when 30 per cent, of the food of 

 the (American) robin, 20 per cent, of that of the cat-bird, and 

 90 per cent, of that of the blue-bird consisted of insects, no 



insects were found in the stomachs of the sparrows, except 

 traces of three grasshoppers, making, perhaps, 6 per cent, of 

 the food." Aruspex. 



FOOD OF THE LEECH. 

 Replying to "J. P. P.," in your issue of 5th inst. : In a small 

 aquarium I had some time since, I found a young leech, in- 

 advertently introduced, feasting on a small snail, which it was 

 moving to and fro in the water, its other end being fastened 

 to the glass, some distance from the bottom of the aquarium. 

 8th October, 188S. F. M. 



— *-^t^«^5«e-» — 



RECENT INVENTIONS. 



The folli wing li't has been compiled ester ially for the SCIENTI fic 

 News bv Messrs. W. P. Thompson ard Boult, Patent Agents, f 

 234, High Holborn, London, IV. C ; Newcastle Chambers, An eel 

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

 and 6, Lord Street, Liverpool. 



Extinguishing Fires. — Means for extinguishing fires 

 in ships' holds and places in which furnaces are em- 

 ployed have been patented by Mr. H. C. Carver. This 

 invention uses the waste gaseous products of combustion 

 in furnaces for extinguishing fires. These products are 

 conveyed through pipes and discharged on to the fires 

 to be extinguished, thus rendering the atmosphere in- 

 capable of supporting combustion, and so extinguishing 

 the fire. 



Ventilators. — An exit ventilator has been patented 

 by Mr. J. W. Gibbs. The object is to form the ventilators 

 so that they have not the rattling noise noticeable in the 

 ordinary mica-flap ventilators when variations of draught 

 occur. This is attained by forming the surfaces which 

 come in contact of a soft, non-inflammable material, which 

 cushions the blow and obviates the noise. The material 

 employed is asbestos, which works well simply fastened 

 like an ordinary mica-flap. 



Musical Instruments. — -A mechanical musical instru- 

 ment has been patented by Mr. J. M. Draper. It con- 

 sists of a reed box containing a double set of reeds of 

 different tone, each of which sets of reeds can, by means 

 of opening and closing shutters covering the outlets of 

 the reed box, be played at will, either alone or with other 

 sets. By opening and closing the shutters the volume of 

 sound is also controlled. Arrangements are made for 

 providing this instrument with bells, cymbals, etc., which 

 may be sounded at will. 



Disinfecting. — A disinfecting machine has been 

 patented by Mr. T. P. Hollick. This invention dispenses 

 with the means usually employed for disinfecting a house, 

 such as sprinkling, or exposing the disinfectant in a basin, 

 and is carried out by means of an endless cotton or 

 flannel band, which passes round rollers arranged above 

 a trough containing the disinfectant. The lower part of 

 the bands rests in the disinfectant. As the top roller is 

 revolved the band is moistened and raised, and exposed 

 to the air in the room, thus disinfecting it. 



Tidal Power. — A means of utilising the rise and fal 

 of the tides for raising water for supplying baths, stree 

 watering, etc., has been patented by Mr. W. Green. / 

 reservoir is provided which fills at high water; a float i 

 also provided, in an enclosure constantly open to tk 

 tidal water. On this float is mounted a hydraulic rae 

 which communicates with the tidal reservoir by 



