Mar. 2, 1888.] 



SCIENTIFIC NEWS. 



SMOKE-PREVENTING APPARATUS. 



OUR illustration, borrowed from La Nature, shows a 

 new device for removing one of the minor troubles 

 of life. The chimneys of our rooms too frequently do not 

 draw well, and in consequence there is smoke. If even a 

 strong gleam of sunshine falls upon the outlet, or if there 

 is a gusty wind or a heavy rain, the action of the flue is 

 impeded. The smoke flows back, and often renders un- 

 inhabitable the room which we have been trying to 

 warm. The usual remedy in such a case is to throw 

 the door and windows wide open, and thus create a 

 current of air which, for a time, re-establishes the 

 draught. This simple and primitive measure is, however, 

 not greatly to be recommended, as the remedy may 

 ■easily prove worse than the disease. 



Many devices have been proposed for overcoming 

 •the nuisance, such, for instance, as the fixed hoods which 



serve for^ a' defence against the sun and rain, and the 

 screw aspirators which are sometimes used when there 

 is'a deficient height of chimney. 



M. Becker, of Paris, has devised an apparatus which 

 consists of an ordinary cowl, fitted at its windward end 

 with a conical inlet-piece through which the wind passes 

 in a jet into the interior of the hood. A draught is thus 

 created in the flue, and its strength increases with that 

 of the wind. 



The action is similar to that of a Giffard injector, 

 and the principle of aspiration thus produced by the 

 wind is also applied in certain self-registering meteoro- 

 logical instruments, such as Bourdon's anemometer. 

 The apparatus is applicable without any modification to 

 the ventilation of drains. 



It is doubtless true that this apparatus increases the 

 chimney draught, and what is still more important, it 

 prevents a down-draught, and so promotes a better com- 

 bustion of the fuel, but it must not be supposed that the 

 mere introduction of air into a cloud of smoke, as shown 

 in the accompanying engraving, will cause the smoke to 

 be consumed. 



THE BITTERLING AND ITS EGGS. 



THE bitterling {Rhodcus amants) is a tiny fish, the 

 smallest of the European carps. It occurs in the 

 the rivers of France, Holland, and Germany. The male 

 is remarkable for its brilliant and varied colouration 

 during the spawning season ; the female for a peculiar 

 appendage, which projects from the under surface of the 

 body, in front of the anal fin, and looks like along orange- 

 coloured worm Von Siebold found, many years ago, in 

 the Strassburg fish-market, a female bitterling, in which 

 this tube was distended by a number of eggs, which 

 gave it a beaded appearance. After the spawning 

 season is over, the tube shrinks, and becomes almost in- 

 visible. 



The use of this singular appendage is known, but, it 

 would seem, not very widely known. Seeley's " Fresh- 

 water Fishes of Europe," for example, a book which 

 contains much useful information drawn from German 

 sources, says (p. 209) : — " No one has observed the 

 mode of deposition of the eggs, or ascertained whether 

 this remarkable tube, which is furnished with its own 

 blood-vessels and nerves, is made use of to place the 

 eggs in a secure position." In reality the problem had 



Bitterling (Carp). 



been solved nearly twenty years before this passage 

 was written, as may be seen by reference to Dr. F. C. 

 Noll's papers in the Zoologische Garten, 1869 and 1877. 

 The tube of the female Bitterling is an ovipositor, used 

 for laying eggs in the gill-chamber of the river-mussel 

 (Unio piciorum). In this situation complete' protection 

 from greedy fishes is obtained, while the water, which 

 the mussel for its own purposes causes to stream inces- 

 santly over the gills, aerates at the same time the embryos 

 of the bitterling. The same nursery is used for the 

 hatching of the young of the mussel itself. Doubtless 

 it would eject the embryo bitterhngs if it could, but, 

 having neither jaws nor limbs, it is powerless against 

 the intruders. 



Dr. Noll has been fortunate enough to observe the act 

 of egg-laying in bitterlings kept in a small aquarium. 

 In spring the fishes pair, and the male accompanies the 

 female assiduously. The ovipositor of the female 

 lengthens rapidly as the spawning time draws near, and 

 the male puts on his gay colours. At length the female 

 places herself, head downwards, close to the hinder end 

 of the mussel, where the inhalent and exhalent aper- 

 tures lie, and suddenly passes a large yellow egg into 

 the gill-chamber of the mussel by means of the ovi- 

 positor. The male then fertilises the egg after the man- 

 ner usual in fishes. Meanwhile the mussel becomes 



