6 NATURE 
[ NovEMBER 5, 1896 
I should like to see in NATURE the views of some scientific men 
on this matter, both of Britain and America. 
The question is certainly of great importance to scientific 
inquirers in nearly all branches of scientific endeavour, and it 
is to be hoped abler minds than mine may lay hold of the 
enterprise. W. K. MORRISON, 
Devonshire, Bermuda Islands, October 15. 
Siemens’ Domestic Gas Fire. 
Dr. Po.e’s letter on the Siemens’ Domestic Fire drew my 
attention to the inquiry on the subject which Mr. Foster 
addressed to you in his letter published in NATURE of Sep- 
tember 17. 
I have had one of these fires in my office at the Society of 
Arts for some years. It was put in under Sir William Siemens’ 
own superintendence, about the time when he described the 
grate in NATURE, soit must have been at the end of 1880 or 
the beginning of 1881. Fora long time I used it with coke in 
the manner intended by the inventor ; but practically I have 
found it more convenient to use ordinary coal, although it is 
doubtless less economical. 
As Dr. Pole points out, the convenience of having gas ready to 
be turned on whenever the fire gets low or goes out, is very 
great ; and in cases where a rather wasteful consumption of gas 
can be prevented, or is not considered of great importance, 
there can be no doubt but that the fitting of a few gas jets to an 
ordinary grate is a very great convenience. There is also a good 
deal of trouble saved in the lighting of the fire, as no paper or 
wood is required ; the grate is simply filled with coal, and the 
gas turned on and lighted. The fire, I should say, burns up at 
least as rapidly as when lighted in the ordinary way. 
If any of your readers are interested in the question, they are 
very welcome to see the grate at work whenever they like to 
call here. H. T. Woop. 
Society of Arts, John Street, Adelphi, London, W.C., 
November 2. 
Diselectrification by Phosphorus. 
IN the course of some experiments made a few weeks ago, 
upon the discharge of electricity by air which had been traversed 
by X-rays, it occurred to me to try whether similar action would 
be exerted by air in which phosphorus was being oxidised. I 
found that a gold-leaf (Dutch metal) electroscope was quickly 
discharged when a stick of phosphorus was held near it. A 
small metal crucible was afterwards connected with the electro- 
scope, and a clean slice of phosphorus half an inch in diameter 
was supported within it at a distance of about half an inch from 
its sides and bottom. The electroscope was completely dis- 
charged in six seconds, the action being more rapid than that 
of a burning strip of nitrate of lead touch-paper one inch in 
width. 
It might be found convenient to attach a lump of phosphorus 
instead of a fuse to the nozzle of a water-dropping collector in 
times of severe frost. 
I do not remember to have met with a previous record of this 
observation. It is of interest in connection with the note on 
slow oxidation, in NATURE of October 29 (p. 631). 
SHELFORD BIDWELL. 
The Departure of Swallows. 
‘*E. P.” mentions in Narure of October 22, a date, some- 
where about October 20, I presume, which he considers is an 
unusual one for swallows. Now, though the bulk of the 
swallows have left by this time, it is by no means unusual to 
see them later on in the year. In 1894 I saw swallows in Kent, 
in the neighbourhood of Tonbridge, on October 20, 21, 25 and 
27, and the last one on November 11; it was flitting about a 
village in a bewildered sort of way, with a crowd of village 
boys throwing mud and clods of earth at it. 
The same year a flock of martins stayed near some buildings 
from October 28 to November 16; by this time many of them 
had died of cold. 
The latest swallows I have seen this year I saw on October 235 
near the same buildings. J. Brown. 
Tonbridge, Kent. 
I BEG to send you the following extracts from my journal 
respecting the late appearance of the swallows. 
1855, December.—It is worthy of record that several swallows 
NO. I410, VOL. 55] 
were seen in this locality towards the end of November and 
during the first week of this month. I have ascertained that 
they were seen in other counties at the end of November ; it 
must not be considered, therefore, as a merely local or solitary 
instance of the late appearance of these birds. 
1863, October.—A few swallows were seen flying above the 
church on the 24th, and again on the 31st. 
1867, November.—Some swallows were observed flying about 
during the last week. 
These observations were made at Uckfield. 
C. LEESON PRINCE. 
The Observatory, Crowborough Hill, Sussex, October 26. 
A Mechanical Problem. 
THE mechanical problem proposed by your correspondent, 
“*Cromerite,” in the last issue of NATURE (October 29), is 
practically answered by the so-called ‘* jumping beans”’ that are 
now being exhibited and sold in many parts of London. In 
this case a hard, rigid seed is seen to travel about in a series of 
small jerks, being slightly lifted from the ground at each move- 
ment. Upon dissection the seed is found to be hollow, the 
original contents having been devoured by a coleopterous larva 
—a soft fleshy maggot—which now partially occupies the cavity, 
and by its spasmodic movements causes the strange antics of 
the natural box in which it is enclosed. The walls of the seed 
appear to be quite rigid and inelastic. E. E. GREEN. 
November 1. 
HERTZ’S MISCELLANEOUS PAPERS 
NYTHING written by Hertz is of interest ; and these 
papers are of interest, not only on this account, 
but also on account of their suggestiveness. It is always 
a question as to the desirability of republishing and 
translating papers published some years ago. Most 
valuable papers of ten years’ standing have produced 
their effect. Their vitality has been transmitted to and 
reproduced in subsequent work, but what the scientific 
world requires is advance rather than revision. The 
work of pioneers is, however, largely an exception to this. 
rule. They are generally in advance of their times, and. 
much of their work is of value long after it was done. 
Such an one was Hertz. Most of his papers are sugges- 
tive of questions which still require answers, and they all 
breathe a spirit that, as he says himself of Helmholtz’s 
work, evokes “the same elevation and wonder as in 
beholding a pure work of art.” His papers are not mere 
enumerations of observations, nor mathematical gym- 
nastics. Each has a definite purpose and an artistic unity. 
A life-giving idea pervades it. It is no mere dry bones, 
but an organic whole that lives for a purpose, and does 
some work for science. 
Prof. Lenard has earned much gratitude for his Intro- 
duction. It gives a charming picture of Hertz, of his 
simplicity, his devotion to science, his loving regard for 
his parents. There is just enough added to the very 
well-selected letters to give the reader a continuous view 
of Hertz’s work, and enable him to follow its development, . 
and hence feel an interest in it and sympathy with the 
worker, thus fulfilling the best ideal of the biographer. 
One of Hertz’s first investigations was as to the kinetic 
energy of an electric current. The question is still of 
great interest. It is known that the magnetic induction 
that accompanies an electric current behaves exactly as 
if it were a mass moving with inertia. This is the inertia 
of magnetic induction. Hertz was, however, looking for 
a different mertia. He looked at the subject from the 
flow of electricity point of view. He thought that there 
might be some phenomenon corresponding to an inertia 
of the electric charges, which upon this theory are sup- 
posed to be flowing in opposite directions through a con- 
ductor. He supposed that these might have some inertia 
1 ‘* Miscellaneous Papers.” By Heinrich Hertz. With an Introduction 
by Prof. Philipp Lenard. Translated by D. E. Jones and G, A. Schott— 
Pp. 364. (London and New York: Maemillan and Co., Ltd. 1896. 
