Oct. 9, 1873] 
is entirely based, and without a reasonable interpretation of 
which no explanation can be considered satisfactory. The 
heemodromograph trace proves that the “tidal wave” of Dr. 
Galabin has a shock origin, as I have shown in the ‘*‘ Journal of 
Anatomy and Physiology” (Nov. 1872), and that the dicrotic 
wave is its resulting tidal wave. 
Dr. Galabin appeals to the ‘‘ tidal wave” in the trace from the 
artery at the foot, in proof of his explanation ; I have taken 
many from that locality, and find that the tidal wave is never 
represented at all (as my explanation requires), for it is thrown 
so far back that it becomes blended with the primary rise. 
My explanation of the details of the cardiograph is ques- 
tioned, because my tracings are said to have been taken with ‘‘a 
lever moving on a pivot, and balanced between two springs.” 
Such was undoubtedly the case in my cardio-sphygmograph 
observations, but not in my paper on the cardiograph trace, when 
the instrument employed was, what Dr. Galabin recommends, 
the ordinary sphygmograph, applied to the chest-wall. 
As long as Dr. Galabin has not full faith in the reliability of 
the sphygmograph and its indications, it is almost impossible 
to maintain an argument with him, for it is hardly worth discuss- 
ing points which may be only the results of instrumental imper- 
fections, These are now understood, and can be easily elimi- 
nated. A, H. GARROD 
Venomous Caterpillars 
THE caterpillars mentioned by R. Benson in your paper of 
August 14, are not at all uncommon in Calcutta. One day my 
little girl was brought to me with what appeared to be a good 
sized hairy caterpillar under her arm, and crying as if in pain, 
and on my trying to remove it in a hurried way, I discovered 
that it was nothing but a mass of small hairs. The child had 
put her arm into an empty tub on the inner edge of which the 
caterpillar was crawling. As soon as she pressed it, she started 
as if she had been stung. All the servants crowded round the 
child and pointed to their heads, but as I was not a proficient in 
their language I could not make out what they meant. I tried 
to do what I could with my fingers to remove the hairs, but 
this seemed very painful, and the swelling round about kept in- 
creasing. The ayah, however, soon appeared, attracted by the 
child’s crying, and seemed to know what was to be done, She 
got some of my hair, madea kind of small brush of it, and gently 
passed it over the injured part. In a few moments the hairs 
were all removed, and nothing was left but a white blister. This 
remained for two or three days and then subsided. In the 
Calcutta schools the boys call these caterpillars ‘* woolly bears,” 
and if stung by them ask for ‘‘a head,” and a few rubs soon 
removes the disagreeable appendages. 
C. H. C. B. 
Calcutta, Sept. 9. 
Harmonic Echoes 
Lorp RAYLEIGH’s notes on Harmonic Echoes recall to my 
‘recollection a little experience which I had in hearing what I 
= supposed to be overtones reflected. ’ 
T have frequent occasion to cross a portion of an open public 
{park in which there are few trees. When any sharp sounds are 
-heard in the neighbourhood, as, for instance, the sound of the 
‘rod in the beating of carpets in a field near at hand, curious re- 
“sponses to the blows of the rod are heard, and these responses 
-or echoes have not the same pitch as the originating sound. I 
was puzzled for some time to account for this echo in an open 
park, with almost nothing above the level of the grass but the 
‘iron railings, till I satisfied myself, by occupying various posi- 
tions, that the echoes were reflections of sound from these narrow 
‘fences. But why the difference in pitch between the originating 
*sound and the echo? This, I concluded, mzg/é result from the 
overtones of the sound being reflected from the thin iron bars 
which constitute the railing. It was also observable that it was 
only the sharp sound emitted by the beating rod which was 
~echoed, and not the dull sound arising from the carpet when 
struck. The hands struck sharply together will also cause an 
echo from the fences, which is higher in pitch than the sound of 
‘the clapping hands. It would be very interesting to experiment 
on this point by sounding, at a proper distance, notes of known 
pitch before narrow, upright, or horizontal bars, and then ascer- 
taining the pitch of the echo, and the relation of the latter to the 
size of the reflecting surface, W. J. M. 
Glasgow 
NATURE 
487 
Ir appears tolerably well established that harmonic echoes are 
selective echoes ; that is to say, echoes which, from whatever 
cause, select and return one of the harmonies of the original 
without the fundamental. 
It may perhaps be found that there are other selective echoes 
than the harmonic kind. In one of the galleries of the very 
large parish church of Monkstown, co. Dublin, the sound of S 
is heard with peculiar intensity, both in the singing and in 
the responses, This is not an echo, but it may perhaps be a 
fact of the same kind with selective echoes. 
Old Forge, Dunmurry Jos¢PpH JoHN MuRPHY 
Carbon Battery Plates 
CouLD you oblige me with information (or state where it 
could be obtained) respecting the process of manufacture of hard 
carbon battery plates, as I have some experiments on hand 
which necessitate the manufacture of plates of a peculiar shape, 
and [ can neither get them made nor obtain sufficient informa- 
tion to enable me to make them well. 
Warrington T. W. FLETCHER 
Brilliant Meteor 
On the evening of September 7, at about 9.7 P.M., while 
walking in a northerly direction in one of the streets of Tiverton, 
I saw a very large and brilliant meteor slowly descend from east 
to west, but in an almost vertical direction. The sky was almost 
entirely covered with a thin veil of cloud, which obscured the 
stars, so that I was not able to note its course with reference to 
then ; but the altitude of the point at which it first appeared 
was about 45°, its path was inclined to the vertical at an angle 
of about 5°, and it disappeared behind a roof at an elevation of 
about 20°, at a point about 9o° to the north of the moon which 
could be seen through the clouds. The light of the meteor was 
greenish and flickering, and far exceeded in intensity that of 
Venus when at her maximum brilliancy, but I could not see any 
train. T. PERKINS 
Reading School 
NORTHERN LIMIT OF PHANEROGAMIC 
VEGETATION 
Cae MARKHAM has most kindly presented to 
the Herbarium of the Royal Gardens, Kew, a small 
but very interesting collection of plants brought back by 
him from his recent Arctic voyage. Amongst them are 
four specimens which he obtained from Dr. Bessel, who 
collected them in lat. 82° N., the most northern position 
from which any phanerogamic vegetation has hitherto 
been procured. The locality appears to have been on 
the east side of Smith’s Sound. The species are Draba 
alpina, L.; Cerastium alpinum, L.; Taraxacum Dens- 
leonis, Desf. var. ; Poa flexuosa, Wahl. 
Jos. D. HOOKER 
THE WEALDEN BORING 
sg gre readers of NATURE will be interested in learning 
that the lowest beds now reached by the Sussex bor- 
ing are not Wealden, but of marine origin ; that the most 
distinct of the shells yet examined by me isa Lingula, that 
itis Zzngula ovalis, a shell of the Kimmeridge clay. The 
specimens which contain it were placed in my hands by 
Mr, Peyton, with Mr. Willett’s consent. We are, in fact, 
already below the Wealden, in the pelagic sea-bed far 
from its ancient shore. 
J. PHILLIPS 
THE NEW MARINE ANIMAL FROM WASH- 
INGTON TERRITORY 
Ne the meeting of the British Association in 1872, 
I exhibited before Section D specimens of some 
long white bodies resembling peeled willow-wands, which 
I had received from Barraud’s Inlet, Washington Terri- 
tory, with the information that they were the “ backbones 
of a fish.” Subsequently I published what intelligence I 
