760 



THE POPULAR SCIENCE MONTHLY. 



storm, in or near the general direction of 

 its motion. 



At stations northward of latitude 36, 

 observations show that great rains are ac- 

 companied by easterly winds ; but, at the 

 more southern stations of the district, the 

 winds are north of east ; while, at the north- 

 ern stations, the winds are from south of 

 east. When the wind blows from any other 

 quarter, it is usually light. 



This paper, like others previously pub- 

 lished, presents, with the diagrams which 

 have been published with them, the general 

 phenomena of atmospheric movements with 

 clearness and precision, and will speedily 

 supersede the vague speculations concern- 

 ing them which have so much occupied the 

 public mind. 



A Eapacions Fish. The Serrasalmo 

 piraya, found in all the rivers of Guiana, 

 is doubtless one of the most voracious of 

 fishes. The genus Serrasalmo (literally 

 " seriated salmon," because of the double 

 row of serratures on the belly) can hardly 

 be classed with Salmonidce, from which they 

 differ both in general appearance and in 

 habits. The S. piraya is a small fish, sel- 

 dom exceeding one foot in length, but yet 

 there is no animal that it will not attack, 

 man not excepted. Alligators, horses, as 

 well as fishes oftentimes ten times their own 

 weight, are preyed upon by the pirayas. 

 In attacking a fish they begin at the caudal 

 fin, and the victim, being thus left without 

 the principal organ of motion, is devoured 

 with ease, several pirayas sharing in the 

 meal. They often bite a piece out of a 

 horse's leg when passing through the wa- 

 ter. The feet of ducks and geese which 

 are kept in the neighborhood where pirayas 

 are plentiful, are almost invariably cut off, 

 and the young ones devoured. In such lo- 

 calities it is unsafe to bathe, or even to 

 wash clothes, in the river, many cases hav- 

 ing occurred of fingers and toes being cut 

 off by them. Schomburgck, in his " Trav- 

 els in South America," from which most of 

 these particulars have been derived, states 

 that these fishes are " caught with hook 

 and line, and their greediness is so great 

 that no art is necessary to conceal the bait. 

 The hook may be baited with a piece of 

 fish, bird, or animal, or merely their en- 



trails ; the piraya will dart at it the instant 

 it is thrown into the water, and seize it with 

 eagerness, but it frequently happens that 

 with its sharp teeth it bites the line, and 

 escapes with the hook in its mouth. We, 

 therefore, surrounded the line where it was 

 fixed to the hook, the length of two or 

 three inches, with tin or lead, and though 

 it had a clumsy appearance we were not 

 less successful. Some precaution is neces- 

 sary even after the fish has been lifted out 

 of the water, or it will inflict in its strug- 

 gles serious wounds ; the angler has, there- 

 fore, a small bludgeon ready, wherewith its 

 skull is broken." 



Science and Ventilation. Sundry mem- 

 bers of the Paris Academy of Sciences, at a 

 recent session, expressed themselves very 

 strongly as to the defective ventilation of 

 the hall in which their meetings are held. 

 Said M. Bouley : " The air here is unfit to 

 breathe ; the thing admits of no excuse ; 

 instead of gas, I wish we had again can- 

 dles, as in former times." M. Leverrier : 

 " I asked for lighting with gas, but I had 

 also asked for another mode of ventilation ; 

 but, with regard to this, there has been no 

 change. However, General Morin is a mem- 

 ber of the Academy, and, in eight days, 

 proper apparatus for ventilation might be 

 set up, if we so wished." General Morin : 

 " Eight days ! Ten years ago, the setting 

 up of such apparatus was in principle de- 

 cided on." Leverrier : " The present con- 

 dition of things is simply disgraceful ; no 

 other hall is so badly ventilated as the hall 

 of the Institute." The eminent astrono- 

 mer, were he to inspect critically the as- 

 sembly halls of scientific and legislative 

 bodies in other countries, would doubtless 

 find abundant reason for retracting this se- 

 vere judgment. 



Intestinal Calculi in Horse?. In Eng- 

 land and Continental Europe large num- 

 bers of horses die annually from the effects 

 of calculi in the large intestine or in the 

 caecum. Of these calculi, Dr. T. L. Phip- 

 son writes in the Chemical News that they 

 often begin by being triangular, or some- 

 times perfectly square, with rounded edges 

 and corners, and become finally circular. 

 In all cases they are formed of highly-crys- 



