DECEMBER I0, 1903] 
NATGORE 
17 
of the spiral valve various Tetrarhynchids, mature, of two 
sizes—I fancy of [two] species—which bears out Shipley’s 
belief of 2 species being in Balistes. In the stomach a 
larval Tetrarhynchid just where a larva should be—the 
adults being further along the canal.’’ 
The rest of the letter, hurriedly written to catch the mail, 
refers to other matters. 
Mr. Arthur Shipley, who is writing a joint paper with 
Mr. Hornell on the parasites of the pearl-oyster for my re- 
port, will no doubt discuss the matter fully later on, when 
he has examined the specimens, but it is, I think, only due 
to Mr. Hornell, who is working most energetically in the 
wilds far from books of reference or any other scientific 
help, that his interesting announcement should be made 
public as soon as possible. W. A. HERDMAN. 
University, Liverpool, December 9. 
The Late Leonid Meteor Shower. 
SuSPECTING that the tail or following segment of this 
swarm, owing to its enormous length, might be outside the 
sphere of influence of Saturn in 1870, and Jupiter in 1808, 
the writer kept watch as follows to see how far this sus- 
picion might prove to be correct :— 
Friday morning, November 13, ..._—... Overcast 
Saturday 5 5B TASS tories No Leonids 
Sunday Ss ne) 15, 12 to 2.30 2 Leonids 
5 to 5.30 No Leonids 
Monday oy rs 16, 12 to 4.15 Intense shower 
Tuesday ‘A An Ds BER Overcast 
Wednesday ,, % 18, 5 to 5.30 3 Leonids 
One of the two Leonids observed at about 12.30 on 
November 15 diverged with a long, slow motion from Zeta 
Leonis to below the stars Nu and Zeta, Ursa, giving one 
the impression of its being an almost ‘‘ end on’”’ one from 
near the radiant, while the other, at about 2 a.m., passed 
high up on the right with a bright flash or streak. <A 
further short watch was kept from 5 to 5.30 with no results; 
hence the conclusion that the shower would be of no very 
imposing character. This, however, proved to be incorrect, 
as on the following morning, November 16, at 12.30, a 
bright flash overhead, and shortly afterwards two fine 
meteors diverging right and left from a point near Zeta 
inside the Sickle, indicated increased activity. 
The display rapidly increased, the meteors coming 
apparently in little flocks or shoals, the majority from an 
area of, say, 6 degrees by 3 degrees along Leo, with an 
hourly rate which he estimated as high as from 80 to 100, 
but this would seem to be below the mark. Between 3 and 
4 a.m. several bright meteors diverged upwards and down- 
wards from the Sickle, thus enabling him to fix the radiant 
as close by its old position at 149°+22°. The following 
morning, November 17, was overcast, but the radiant was 
still active on November 18, one of the three Leonids 
observed radiating upwards over Eta from within the Sickle 
as usual. A remarkable feature was that many of the 
meteors diverged upwards towards the S.W., whilst others 
diverged downwards N.E., as if conforming to the ecliptic, 
an appearance which may have been due to the rotation of 
the earth, and had been noticed before in connection with 
other well-known showers. Many of the larger meteors lit 
up the atmosphere with fine, bright, steel-like flashes. 
At 4.15 the sky became overcast, but as he turned in he 
could stitl see meteors falling in the west and north-west, 
and it would appear, from observations made elsewhere, 
that the maximum occurred during the next two hours, i.e. 
from 4 to 6. It may here be remarked that this shower 
seemed in previous years to be at its best about an hour or 
so before daylight, owing, no doubt, to its then high 
altitude. , 
Altogether, the display was much above the average, and 
would appear to have justified the anticipation that the tail 
end held on its course. At any rate, we get another glimpse 
into the mechanics of a meteor stream, and more particularly 
into that of the Leonid, and the distribution around the 
orbit of the latter, should it still intersect the path of the 
earth, is a question for the future. 
W. H. MItican. 
2 Barronville, Holywood, Co. Down, November 30. 
NO. 1780, VOL. 69] 
Mr. Henry’s letter in your fssue of November 26 contains 
several notable points which confirm my own observations. 
Being engaged on other work (which entailed long spells 
within the observatory and the dark room) throughout the 
night of November 14 and early morning of November 15, I 
noticed only a few meteors, and, as the sky became over- 
cast here at 4.45 a.m., it is evident that, according to Mr. 
Denning’s account, observations of the maximum display 
were impossible at South Kensington. 
However, on the early morning of November 16, 2.15- 
3.50 a.m., my watch was rewarded by the appearance of 
more than fifty Leonids, some of which were exceedingly 
bright and lasting. Facing the south-east, I had familiar 
constellations (Orion, &c.) in the field of view, and was con- 
sequently able to record the trails among the stars with 
a fair amount of certainty. 
The most striking point on which Mr. tenry’s observ- 
ations are confirmed by mine is that there were decidedly 
two apparent separate radiants, the one very near to, or 
coincident with, that given by Mr. Denning in Nature for 
November 12, and another, from which quite half of the 
observed meteors seemed to emanate, at about ReAw— mac. 
Dec.=+17°. Several Leonids with short trails were seen 
quite near to ‘‘ the Sickle,’’ and indicated by their direction 
the existence of this second radiant point. One long-trail 
Leonid occulted & Geminorum, and if the trail had been 
prolonged (it stopped short about two or three degrees from 
Betelgeuse) it would have passed between a, y¥, and 
A Jrionis. The majority of the meteors observed by me 
passed from the direction of Leo towards Gemini, Orion, or 
Canis Minor. Wittiam E. ROLston. 
Solar Physics Observatory, South Kensington, S.W., 
December 5. 
Weather Changes and the Appearance of Scum on 
Ponds. 
Some years ago I also observed the phenomenon of a 
sudden appearance of scum on the surface of a pond similar 
to that mentioned by ‘‘ Platanus orientalis’? in NATURE, 
November 5. Big. 
The explanation, however, given by Dr. Mill in the same 
number of Nature, namely, that the appearance of scum 
is occasioned by an accelerated flow of springs rising 
through the chalk of the floor of the pond, does not apply 
to the case which I have observed. That pond had no 
springs of the kind, but was fed by a very small and slow 
creek emptying into the pond at its upper extremity. 
Although the pond was pretty large, the scum did not appear 
near the inlet only, but all over the pond at the same time. 
I wish to offer the following explanation of the pheno- 
menon so far as it came under my observation, and I am 
inclined to believe that it applies to the case of ‘‘ Platanus ’” 
just as well. : 
Our pond was very rich in marsh gas, a fact which could 
be easily ascertained by thrusting an oar into the soft 
bottom, when large bubbles of this gas would come to the 
surface. Now it is quite natural that this gas, slowly gener- 
ated as it is, within the layer of decaying vegetable matter 
at the bottom of the pond, will gather in little bubbles, and 
these in turn will rise, provided they have acquired a 
sufficient buoyancy to break through their mouldy matrix, 
tearing off and carrying some of the solid matter up to the 
surface. 
Ordinarily, this will take place all the time at regular 
intervals, but at a very slow rate, and would, therefore, 
escape observation. in time of a sudden fall of atmospheric 
pressure, however, the case is different. Then all the gas 
bubbles which are more or less ready to rise under normal 
conditions will suddenly expand and rise simultaneously, 
carrying upward not only a few isolated particles, but entire: 
layers of soft material. I have often observed this very 
phenomenon, although I failed to notice the atmospheric 
condition at the time. 
The material itself which was thus thrown to the surface 
consisted, so far as I can recollect, of black-brown vegetable 
matter, derived chiefly from leaves that had fallen into the 
pond, and of a green slime, consisting of numerous alge. 
Frep. J. HILic. 
St. John’s College, Toledo, Ohio, U.S.A. 
