August 10, 188:}. 



SCIENCE. 



loi) 



In (4) the coefficient of V— 1 may have any 

 magnitude, and in (5) the coefficient of y' — 1 

 is the reciprocal of that magnitude. And since 

 from anj- cubic (Theorem I.) (4) or (o) may 

 be obtained, it follows, that, when the real part 

 is unity, the coeflicient of V~l iU'\v be made 

 less tlian unity, and real (Theorem II.). 



Put n = coefficient of y'— 1, we have, by 

 expansion, 



(l+«)' + (l-«)' = 



I 4.7.10.13 \ , ^ 

 H3.6.9.12.15Tl8r'^^'^- 

 The series, already converging, is made doublj- 

 converging by the high powers of »i, since n 

 has been made a fraction. Putting n, for 

 example, no smaller than j\,, the correction 

 for the sum of the series at the eighth term 



1 



would be less than i^4oo,o00,000,000,000,000' 

 And, as the precision of the value of .r is de- 

 termined proportionally to the accuracy with 

 which tlie series is summed, it follows that a 

 good approximation to x may be obtained by 

 using a Acrj- few first terms of the series. 



A. M. Sawik. 



THE HABITS OF MURAENOPSIS TRI- 

 DACTYLUS IN CAPTIVITY; WITH OB- 

 SERVATIONS ON ITS ANATOMY. 



The Louisianian district of the Austrori- 

 parian region is a particularly rich field for 

 the herpetologist. Thirty-six species of rep- 

 tiles are known to be confined to its limits 

 alone, not to mention a 

 long list of others that 

 range generally over the 

 southern states ; and to 

 these we must add those 

 species which are men- 

 tioned by the old French 

 authors, but have not 

 yet been taken by 

 American naturalists, a 

 knowledge of which fact 

 alwaj's enhances the in- 

 terest of a country in 

 the eyes of the explorer, 

 who pushes his way 

 through its tangled jun- 

 gles, or visits its uufreejuented spots and its 

 sultry forests, for the first time. 



After my arrival in New Orleans, the months 

 that are included in the pseudo-winter of this 



sub-tropical land came and passed by. before 

 my collection could boast of a single specimen 

 representing the .Vmphiumida : indeed, it was 

 not until April had almost made its appear- 

 ance that a superannuated old negro presented 

 himself one morning with a live but rather 

 small specimen of the three-toed siren, the 

 subject of this essay. 



He called it a ' Congo eel,' — a name which 

 is inditferently applied by every one here, 

 intelligent as well as ignorant, to both this 

 reptile and Amphiuma means. Long before 

 this, reports had come to me from fur and near 

 of the dreaded • Congo .' or ' lamprey " as it \» 

 often called. It was universally said that its 

 bite was invariably fatal. To such an extent 

 was this believed, that. I am told, a physi- 

 cian of the city, of undoubted reputation in 

 his profession, and a capital chemist, but pos- 

 sessing nothing more than agener.il knowledge 

 of natural science, was actually making experi- 

 ments with the view of examining the venom 

 of this innocent amphibian. When my aims 

 became pretty thoroughly known tlu'oughout 

 my section of the country, I applied a very 

 different kind of analysis to this problem : a 

 good round sum of mone}- was offered to an}' 

 one who would bring me the full record of a 

 well authenticated case of death from the bite 

 of the Congo snake, or eel. It is almost need- 

 less to add, that I never had to pay the re- 

 ward. One person, more mercenary than well 

 informed in such matters, did bring forward a 

 case of an hysterical old colored woman who 

 had been bitten several years ago by a Congo 

 eel, and died .s(i- months after the infliction of 

 the wound, in spasms ! 



The small one, which now came into mv 



Klo. 1. — Life oiic head uf Muraeiiopei« tridactylus; adult. Drawn from the living apfclinen 

 by the author. 



possession, was placed in water, in a large 

 comfortable vessel, for observations upon his 

 habits, before he was finally consigned to his 

 tank of alcohol. In handling him, he rarely 



