52 
NATURE 
[ May 21, 1885 
accumulators. The tendency to form these brushes may’ be 
much diminished by cementing a small disk of sheet caoutchouc 
over the inner ends of each metal-inducing strap. ; 
The machine in full work presents several points of interest, 
the explanation of which, perhaps, is not very obvious. The 
first I would notice is, that although 15-inch plates will scarcely 
give an wassisted spark of more than 1% inches in length, the 
interposition of a trifling condenser, showing only a coated 
surface of 6 square inches, will entirely change the character of 
this spark, the almost continuous stream of short sparks giving 
place to fewer, zigzag, snapping, 4-inch discharges, of much in- 
creased density and brilliance. The attachment of a condensing 
tube, constructed as follows, will be found a valuable addition to 
such machines as collect separately the positive and negative 
electricities. 
About 18 inches of thin glass combustion-tubing of }-inch 
diameter is taken. Within, and at 4 inches distance from each 
end, a space of 2 inches is coated with tinfoil, leaving a space 
of 5 inches or so of clear glass between them. Two similar 
pieces of foil are fixed by a thin coat of gold-size on the exterior 
of this tube. They superpose the inner pieces of foil, and act as 
the outer coats of two small Leyden jars united as it were in one. 
These outer coatings are connected by a strip of tinfoil, The 
inner coats are placed in contact respectively with the plus and 
minus collectors of the machine, by means of thick brass wires 
thrust through caoutchouc plugs. The wires are so bent that 
their ends may drop into suitable holes, from which they may be 
at any time detached. 
A thin coat of spirit lac-varnish spread within and without 
much favours the insulation of the tube. 
Thus arranged, bright angular sparks of 4 or more inches in 
length will pass between the knobs of the discharger at every 
three-quarter turns of the handle. 
Another point of interest offers itself when the knobs of the 
discharger are placed beyond their usual striking distance. In 
such a case the spark very frequently passes within the tube 
from coating to coating, quite silently, and with an optical 
illusion of comparative slowness of transit. When first I noticed 
these bright flashes of light, they suggested the form of an un- 
dulating fire-ball, and this brought to my remembrance the 
often-described but obscure phenomenon of “ ball-lightning.” 
I could not, however, detect any real retardation of the discharge 
by a somewhat rough experiment with the ordinary spark-wheel. 
When two large jars are connected with the machine the dis- 
ruptive discharge of 4 inches is accompanied by a sharp report, 
like that of a small pistol. I was not prepared for the fact that 
such a noisy discharge made to pass through the condensing-tube 
is quite silent, just as if it flashed through a partial vacuum. It 
may also be noted that the spark through the tube may be made 
much to exceed the length of the discharge in the ordinary way. 
The last point I now mention, and concerning which I should 
value the remarks of Mr. Wimshurst, or any other competent elec- 
trician, is the increasing intensity of charge taken up by the metal 
inducers, or sectors, as they pass each other between the point 
of their contact with the earth through the metallic brush and the 
next following comb-collector. In the electrophorus such a 
contact is required once between the delivery of each spark ; 
whereas in the machine here used, having perhaps twenty-eight 
sectors, a contact is given only once in seven inductive processes. 
It will be found that well-varnished jars, without the usual 
wooden tops, are much the most efficient. Nevertheless, even 
these sometimes become so highly charged, that the electricity 
will force itself over their edges, doubling back, as it were, over 
a distance of 5 inches. 
A pretty, but somewhat trifling experiment may be made by 
attaching two jars of unequal capacities to the collectors. Thus 
a jar of half a pint capacity placed on one side may be flanked 
by a quart jar onthe other. Here the small jar, if the coatings 
be not too distant from the lip, will discharge itself three different 
times, whilst the large jar is getting sufficient tension to strike, 
say, at 34 inches. Both jars will then discharge together across 
the upper knobs. It may thus be shown that four half-pints of 
electricity make one quart of the same, as in liquid measure. 
G, B. BucktTon 
Nesting of Micropternus Phzoceps 
IN continuation of the communication from my frlend, Mr. 
Wm. Davison, regarding the nesting of woodpeckers in ants’ 
nests, published in NATURE (vol. xxxi. p. 438), perhaps the 
following notes of mine may be of interest :— 
Camp Meplay, Thoung-yeen Valley, Tenasserim, 
April 20, 1882 
This morning, in going from my camp to the Meplay Forest 
Reserve, I had to pass through several densely overgrown 
phonzohs.* While making my way along with some difficulty, 
I startled a brown woodpecker (AZicropternus pheoceps) from a 
small pyingado tree (Xy/a dolabriformis). Looking up into the 
branches I saw a large ants’ nest, in the centre of which appeared 
a circular hole so exactly like the borings made by woodpeckers 
ordinarily in the trunks of trees, that I sent up a Karen boy 
who was with me to ascertain whether it was possible the 
Micropternus had been boring into the ants’ nest, as, I had 
heard was the bird’s curious habit. The ants’ nest was only 
about ten feet above the ground, placed in a fork of the 
pyingado, two small branches of which passed clean through it. 
Climbing up, putting in his fingers and then a twig, my Karen 
follower announced that there were two eggs. Leaving the nest 
alone for the time being, in the evening I returned by the same 
route, and was able not only to cut off and carry into camp the 
whole nest as it was ; but I managed to secure also the hen bird 
as she flew from the eggs. Arrived in camp, I got the two eggs 
out, and then very carefully made a cross-section through the 
#, entrance tunnel made by woodpecker ; 4, retort-shaped nesting-chamber 
of woodpecker; c, excavations made by the ants; ddd...... d, en- 
trances to them; ///...... 4 tunnels made by the ants; gg, fork of 
pyingado branch—one twig passing through the egg-chamber excavated 
by the woodpecker. 
ants’ nest so as to divide the boring made by the woodpecker 
longitudinally. 
The accompanying is a rough diagrammatic sketch of the 
appearance of the cross-section of the nest as hollowed out 
by the woodpeckers. The ants’ nest was a large, spheri- 
cal, solid mass of leaves and clay, the leaves outside being 
arranged one over the other something like the tiles on the roof 
of a house, but riddled in many places with the entrance tunnels 
made by the ants—a small black and red species of M/yrmica, 
the trivial or specific name of which I do not know. It is 
; probably closely allied to the AZjzmica mentioned by Sir J. 
Lubbock in his ‘‘ Ants, Bees, Wasps” as having been described 
by Sykes in the Zrans. Ent. Soc., vol. i. Very few of the ants 
* The wild hill-tribes of Burmah and Tenasserin have a wasteful system of 
cultivation called ‘‘toung-yah.” Yearly, in February, the heads of families 
in a village choose, each head for himself, a spot of well-grown, often virgin 
forest, generally on a hill-side, and within as convenient a distance of the 
village as is obtainable, cut down all the trees big and small, and allow them 
to dry during the hot months of March, April, and May, and towards the 
latter end of the last month set fire to them. The ashes thus obtained from 
the timber forms a splendid manure for paddy, and soung-yak rice is preferred 
by the Karens to ordinary gum (field) rice. The “‘toung-yah,” or clearing 
after the paddy has been gathered in, is abandoned, and in two or three 
months, under a hot sun and excessive moisture, becomes an inaccessible 
jungle, full of thorny bamboos, creepers, and elephant grass. Such deserted 
toungyahs are called phonzo/ts, and are not again cultivable ‘for from ten to 
fifteen years. 
