7 
May 13,1873) 
NATURE 
45 
disclaim (having no title to it) the experience he assigns to me in 
reference to the dangerously ulcerated throat, never having made 
myself a martyr to science by so experimenting in propria per- 
sona, Ihave no doubt, however, as I have elsewhere stated, 
that this method of treating a cobra bite would not be devoid of 
danger to the operator. 
As to venomous caterpillars. There is one much dreaded by 
sportsmen in the Himalayan Terai. [t is said to be apt to fall 
from the trees on to persons passing or resting beneath their 
branches, and causes great irritation of the parts with which it 
comes in contact, amounting, I have been told, in some cases to 
erysipelatous inflammation. [tis a moderate-sized, dark-coloured, 
hairy caterpillar, and known (I believe) in those parts of the 
Terai where I have been, as the 4om/a. Ihave never seen it, 
but during my tiger-shooting expeditions into the Terai, it was 
always one of the probable inconveniences to be looked for in a 
camp in the tree jungle. 1 have heard many stories of the 
painful and irritating effects of contact with this creature, whose 
hairs are said to cause those results not only by breaking into but 
by also inoculating some irritating secretion into the skin. 
London, May 4 J. FAYRER 
I HAVE just read with interest your report of the paper on 
“Venomous Caterpillars,” which appeared in your last. 
Towards the end of the report Mr. A. Murray refers to a hairy 
caterpillar which he received from Brazil, and remarks that ‘‘ if 
the caterpillars have a special venom, then, as in the nettle, 
there should be a gland at the base of each hair, which should 
be hollow.” I think I know the caterpillar to which he refers, 
and if I am right, its hairs are not exactly venomous, but pro- 
duce a considerable amount of irritation in the skin. When in 
Brazil in 1859, I collected some of these caterpillars. They are 
very similar in appearance to the larvze of the British Arctia, but 
when their hairs are examined under a microscope, they are 
found to consist of a series of barbed points, the point of each 
succeeding barb fitting into the divergence of the preceding 
barbs ; at least, that is my recollection, for I have not examined 
them since then, and cannot find any specimens to do so now. 
The caterpillar is called in Maranham, “‘largata de fogo,” that 
is, ‘‘fire caterpillar.” After these hairs have afforded their pro- 
tection to the caterpillar during its life, it carefully removes them 
from its body and weaves them in its cocoon, so that the pupa 
is thus as safe from intruders as the larva itself was. Whena 
child, I recollect that Maranham was occasionally visited by great 
numbers of a particular kind of moth, the dust of whose wings 
produced a very great irritation on the skin, the least touch of 
one being sufficient to render you miserable for the rest of the 
evening. I perfectly remember a drove of these putting a quick 
temination to a small dance at home, as you may easily conjecture 
that ladies in evening costume are not well protected against such 
visitors. When in Maranham in 1859, I heard that these moths 
had not been seen there for many years. I believe their visits 
were during the rainy season. Some of the British Bombices, 
&. quercus, for example, and some of other genera, are said to 
possess irritable hair. But in 4. guercus the hairs are not 
barbed, and, not being an entomologist, I can give no informa- 
tion respecting the others. Henry S. WILSON 
Anatomical School, Cambridge, May 5 ; 
On some Errors of Statement concerning Organ-pipes 
in Recent Treatises on Natural Philosophy 
THAT our best teachers of science, both in their books and lec- 
tures make statements which are erroneous in fact, and inferences 
which are misleading whenever they touch upon the subject of 
wind instruments is not a little surprising, considering that in- 
tellects so highly trained hold in aversion any approach to inex- 
actness, and the strangeness of it is that the errors arise through 
an ancient human custom, now supposed obsolete among philo- 
sophers, of ‘‘ speaking without knowledge.” 
The evidence, if tendered, would fill some few pages of this 
paper, and if names were appended to the quotations the list 
would include authors most esteemed and honoured, 
To cite two instances among many—and they are from works 
of unquestioned value and authority, and supposed to bring down 
sciences to the latest date—in the recently completed translation 
by Prof. Everett of Prof. Privat-Deschanel’s ‘* Natural Philo- 
sophy,” the following passage occurs in explanation of the 
organ-pipe :—“* The air from the bellows arrives through the 
conical tube at the lower end, and before entering the main body 
of the pipe has to pass through a uarrow slit, in issuing from 
which it impinges on the thin end of the wedge placed directly 
opposite, called the lip. This lip is itself capable of vibrating 
in unison with any note lying within a wide range, and the note 
which is actually emitted is determined by the resonance of the 
column of air in the pipe.” In another equally valuable work, 
the ‘‘ Physics,” by Prof. Ganot, translated by Prof. Atkinson, 
thisdescription is given respecting the free-reed—“ the tongue 
which vibrates alternately before and behind the aperture, merely 
grazing the edges as seen in the harmonium, concertina, &c., 
such a reed is called a free reed.” Four professors responsible 
for statements so perversely at variance with facts that it is not 
possible either writer can have even attempted to ascertain, still 
less to demonstrate that the facts are as asserted. Practical ex- 
perience affirms that the lip of the organ-pipe does not vibrate ; 
press it with your hand or hold it in a vice to deaden the 
assumed vibration, and you will not alter one iota of the pitch 
of the sounding note: that the free-reed does not in its vibra- 
tion ** merely graze the frame ;” it would be fatal to its proper 
speech if it did, and its vibrations would be checked in a jarring 
rattle. The facts are too simple to need argument ; all that was 
required was observation. 
When Ganot, describing a metal free reed, affirms as a law 
that when the force of air 1s increased the pitch of the reed rises, 
his statement is inexact, for it depends entirely on the accident 
of taking up a reed more or less rigid in proportion to scale, 
whether the experimentalist shall prove his assertion or prove 
the reverse. In the harmonium, of a set of five octaves of reeds, 
half will go more or less sharp, and half will go more or less 
flat, as the force of wind is increased, a fact which, if 
more generally known, might induce players to mitigate 
some of the insufferable harshness and jangling inflicted on 
listeners. That ‘‘a sharp edge” is essential to the functions of 
the flue organ pipe is one of the commonest errors entertained 
by philosophers, and it forms the groundwork for whole pages 
of false theory. In treatise after treatise it is stated “‘the air is 
driven against the sharp edge,” ‘“‘is split upon the sharp edge, 
and by concussion caused to proceed intermittingly,” ‘‘the air 
strikes the sharp edge,” “ is divided,” ‘*is lacerated,” ‘‘strikes 
against the upper lip, and a shock is produced which causes the 
air to issue in an intermittent manner.” Another equally com- 
mon misstatement, and important because so strongly influencing 
theory, is that “a closed pipe gives a note an octave in pitch lower 
than an open pipe of the same length; the length of a closed 
organ-pipe is one-fourth that of the sonorous wave it produces in 
the air.” Proved facts give different results. At my hand this 
morning there stood a sounding-pip2 perfect in finish, its lip 
quite blunt, by measurement at the edge half an inch in thick- 
ness ; and whole ranks of pipes were there in various grades of 
conformation, showing that the sharp edge was immaterial to the 
functions of a speaking-pipe. Sometimes the chamfering of 
the lip is desirable, sometimes not, and the builder decides ac- 
cording to the quality and character of each stop. ‘The art in 
“voicing ” a pipe consists in so directing the stream of air that 
it shall avoid striking the lip, and shall smoothly glide past with- 
out shock or noise, or concussion ; you get no tone until it does. 
Actual experiment will show that a closed pipe gives a note only 
a major seventh below the note it gives as an open pipe, not an 
octave below ; indeed, in the higher range of pipes it will be a 
whole tone short of the octave, to sound which the pipe would 
need to be made considerably longer. As having some signifi- 
cance in connection with this, it may be mentioned that there is in 
an open pipe, whilst sounding, a centre of equilibrium of pressure ; 
it does not occur, as supposed, at the true half of the length, 
but somewhat below that division; as evidence, take the Flute 
Harmonique, when desiring to strike the node, it will always be 
found below the half. Further, as to length. If the open 
diapason pipe beside me, giving as fine a tone (CCC) as musi- 
cian can desire, measures 14 ft. 1oin. in length, and its corre- 
sponding sound-wave claims 16ft. or nearer 17ft., the wide 
divergence merits better investigation than it has hitherto re- 
ceived. The experiments of Regnault and Seebeck are highly 
important to this question, but do not reach the conditions 
pressing for explanation in a speaking organ-pipe. To attempt 
to demonstrate the laws of organ-pipes with a tuning-fork is as 
inconclusive as sending galvanic electricity through a dead body 
and calling the movement life. 
There is little difficulty in understanding how it happens that 
errors respecting wind instruments arise and are perpetuated. 
Experimental philosophers are occupied with the weightier mat- 
ters of science, are rarely musicians or familiar with wind instru- 
