546 
methods, I still am bold enough to ask whether anything can be 
‘¢more misleading and inaccurate’ than the formula for reduc- 
tion for temperature and pressure given in both editions of his 
“Organic Chemistry” under the description of Dumas’s vapour- 
density method. And to add that no excuse can here be found 
of a correction given elsewhere, or of the fact that it may be 
desirable sometimes to state a case broadly to begin with and to 
define it more closely afterwards. HEnryY E. Roscor 
The Tangent-Galvanometer 
ATTENTION has recently been drawn more than once (notably 
by Sir William Thomson, and by Mr. W. H. Preece and Mr. 
Kemp) to the advantages offered, in certain cases of the use of 
the tangent-galvanometer, by placing the instrument so that the 
plane of the coils makes a greater or less angle with the plane 
of the magnetic meridian. It may not be amiss, therefore, to 
point out that, in 1869, M. Bertin showed that the sensitiveness 
of the tangent-galvanometer for strong currents may be increased 
and the usable range of deflection doubled by placing the circle 
in a vertical plane inclined at an angle of 45° to the magnetic 
meridian (Avnales de Chimie et de Physique, 4th series, vol. 
xiv. p. 27). 
When readings are taken with the current traversing the 
galvanometer, first in one direction and then in the other, as 
would always be done if accuracy were important, the expression 
for the strength of current is almost as simple when the coils 
make an angle with the magnetic meridian as when they are 
parallel to it. In the former case the strength of current is 
C = 4k cos a (tan @ + tan @’), 
where a is the (fixed) angle between the plane of the coil and 
the magnetic meridian, and @ and 6 the deflections of the needle 
from the plane of the coil due to the current in the two direc- 
tions. @ is reckoned positive in the direction from the plane of 
the coil towards the plane of the meridian, and 6’ is reckoned in 
the opposite direction. To determine the angle a we have 
tana = 3 (tan @ — tan 6’), 
and it is probably most convenient to determine the numerical 
value of cos a in the first expression from this by tables. If the 
current be adjusted so as to make the second deflection @’ = o, 
we have simply tan a = 4 tan 6, if 6, be the corresponding 
deflection with the current reversed. G, CAREY FOSTER 
University College, London, September 30 
Alligators in the Bahamas 
In Catesby’s ‘‘ Natural History of Florida, Carolina, and the 
Bahama Islands,” published in the latter half of the eighteenth 
century, the author, usually a most accurate observer, states that 
the mangrove-swamps on the Island of Andros presented a 
loathsome appearance owing to the remains of fish having been 
left there, half eaten, by the alligators. During a fairly com- 
plete exploration of Andros, which I made in the early part of 
last year, I observed no traces of these animals, though, as I 
was not then aware of Catesby’s statement, I did not make any 
special search for them. In response, however, to inquiries 
made in the local paper, I lately received from the Rev. W. L. 
de Glanville, Rector of Inagua, Bahamas, a letter from which 
the following is an extract :— 
“Legendary stories of alligators having been floated to this 
island on logs of mahogany are numerous here. I have not 
succeeded in verifying any of them. On July 21, while on a 
visit to our North-West Point Settlement, a man exhibited 
to me the skin of an alligator which he had shot a day or two 
previously. Length all over, from tip to tip, 8 feet ; from line 
at right angles to tip of snout to angle of jaw, 13 inches; 
greatest frontal diameter, about 11 inches. 
“Logs of mahogany have been drifted recently on these 
shores, but no one saw an alligator arrive. That shot was on 
shore, and seen more than once.” 
As the distance from this to Inagua is more than 400 miles, I 
have not been able to make inquiries on the spot. But there 
seems to be no doubt that the alligator must have been 
carried by the current from the south-east on a log of mahogany 
or other wood from San Domingo to Inagua. It seems likely 
that alligators have frequently been drifted to that island, though 
the absence of a suitable environment has prevented their sur- 
viving. The conditions in Andros would suit them better, since | 
NATURE 
[Oct. 7, 1886 
about that island there is a considerable extent of fresh and 
brackish water in lakes, lagoons, and creeks. But it is not easy 
to understand how they could arrive at Andros, unless we sup- 
pose that the Gulf Stream carried them from the north-west 
coast of Cuba and cast them on the west side of the Great Bahama 
Bank, whence small local currents and the wind might bring 
them to the west side of Andros. The distance travelled would 
in this case be about 300 miles, or about twice as great as that 
from San Domingo to Inagua. 
I trust that this note may be useful as affording further proof 
of the fact that oceanic currents take some part in the dispersion 
of even large animals. JoHN GARDINER 
Nassau, Bahamas, September 15 
Meteors—The September Taurids 
On September 22, 1886, roh. 26m., I observed a fine meteor 
about equal to Jupiter, pursuing a path of some 7° in the ex- 
treme east region of Aries. It left a streak and moved some- 
what slowly, being evidently foreshortened near its radiant 
point in Taurus. At 10h. 46m. the same night I noticed 
another meteor from the same direction. 
On September 21, 1879, I counted 92 meteors, including 
several from this radiant in Taurus, and on September 22, 1884, 
two others were seen amongst 29 registered on that date. 
A comparison of the paths shows a well-defined radiant at 
63° + 23° (about 8° N.N.W. of Aldebaran), and I believe the 
shower is rather an important one, though not well visible until 
late in the night. 
I have recognised several radiants from this position in 
Taurus in October and November, and in August Mr. Greg 
derived a shower at 64° + 22° from the observations in 1867-74, 
collected by the Luminous Meteor Committee of the British 
Association. On October 17-19, 1877, I found a radiant at 
63° + 22°; on November 20, 1876, at 62° + 224°; and on 
November 27, 1880, at 63° + 21°. There are also many other 
contemporary showers slightly south-west at about 59° + 20°, 
and it is in November that the display of meteors from Taurus | 
reaches a maximum, 
In September, during the last half of the month, I have deter- 
mined some other showers in the region of Taurus, supplying 
meteors of much the same character. The chief additional 
centres of radiation seem to be at 74° + 14°, 70° + 4, and 
53° + 3°, and there is a fairly active shower also from a point 
further east, at 89° + 19°, in Orion. The first of these, near 
11 Orionis, was splendidly defined from 8 bright meteors on 
September 27, 1886; and on September 22, 1871, Lieut.-Col. 
Tupman saw it at 75° + 15°. 
well seen in September 1877, and confirmed in September 1884, 
but this is essentially a morning shower, as the radiant does not 
reach a fair altitude for the dispersion of its meteors until the 
few hours preceding sunrise. W. F. DENNING 
Bristol, October 3 
Action of Light upon Diastases 
In 1878, in conjunction with Mr. T. P. Blunt (Proc. Roy. Soe, 
No. 191), I showed that the zzve-tive ferment of cane-sugar is 
destroyed by oxidation on prolonged exposure to sunlight. 
Lately I have extended this observation to other ferments of the 
like kind, with similar result. 
Twenty-five cubic centimetres of very active solutions of malt 
diastase, pancreatic diastase, and trypsin respectively were ren- 
dered inert by insolation in 50 cc. flasks for one month (August 
25 to September 25). 
A solution of Aepsiz was likewise destroyed, but in this case 
the ferment had been badly prepared, and was not very potent 
to commence with. 
On the other hand, 25 cubic centimetres of solution of venme?, 
though distinctly enfeebled by insolation, still retained its specific 
properties at the end of the month. This immunity, however, 
was only relative, for a more dilute solution in a shallower stra- 
tum was almost entirely destroyed by one week’s exposure to 
light (August 31 to September 7). 
In all cases the contents of similar flasks kept under like con- 
ditions of temperature, &c., but in the dark, were found to be 
still active at the termination of the experiment. 
In determining the peptonising power of the trypsin and — 
pepsin, Griitzner’s method (carmine-stained fibrin) was very 
useful. I find, however, that it is more convenient and econo- 
The Orionids at 89° + 19° were 
