NATURE 
201 
Governor, which is between the two former places with respect 
to both position and eleyation, ‘=70°°5, # = 27°41 in., from 
observations kindly made for me by Captain Lanyon, A.D.C. ; 
so that the calculated difference of temperature between Kingston 
and Craigton is 8°°3, the observed difference ; and the calcu- 
lated difference between Craigton and Newcastle is 3°°55, which 
is only 0°05 too large. And since the equation has been found 
to hold good under different circumstances at lower elevation, 
we may suppose that it is strictly true for Jamaica. 
With regard to balloon ascents, I have before me two tables, 
one compiled by Sir John Herschel, and the other by Prof. 
Loomis, from more recent observations, and these are brought 
- into the same form in the following table in order to compare 
them ; the first column contains the fall of the barometer in 
inches, the second contains the corresponding fall of temperature 
from Herschel’s Meteorology, the third from Loomis’s Meteoro- 
logy, and the fourth contains the mean of the numbers in the 
second and third, which we shall consider to be the average 
results obtained from balloon ascents, 
t 2 3 4 5 6 
ho-b H L to-# Calc. Diff. 
in. o ° ° ° 
2 30 10°! 66 16°3 +03 
4 68 iy de 12°1 12°6 —0'5 
6 IX°3.0\|, 23:2 17°3 18-9 — 16 
8 16°9 29°0 230 25°2 — 2°2 
10 23°6 34°7 29°2 315 — 23 
12 314 40'5 36'0 37°38 - 13 
14 408 463 || 43°6 441 =A 
16 518 ery) ie 51° 50°4 + 14 
18 637 | 561 | 59°99 56°7 + 32 
Now if we take ¢,—¢ = (fo—J), we shall get nine equations 
of condition for finding A; the most probable value of this 
quantity is 3°15, which hardly differs from the value found in 
Jamaica. Again, if we calculate 4.-—¢ and employ this value of 
A, we get the fifth column, and it will be noticed that the 
differences in the last column between the observed and calcu- 
lated quantities are very small when we consider the great 
differences between the second and third column. 
| Therefore the equation 4, —- ¢= A(fo—/) holds good for 
about two-thirds of the whole atmosphere, and if it holds good 
for the remaining third, by putting # = 0, we shall obtain the 
difference between the temperatures at the lowest and highest 
strata of the atmosphere ; this difference is about 94°, so when 
the temperature at the surface of the earth is 50°, the tempera- 
ture at the superior limit of the atmosphere must be — 44°. 
Since the temperature falls 3°15 for every inch the barometer 
may fall, or for every 945 ft. we may ascend (when that tempe- 
rature is about 50° and the elevation low), the temperature in 
England will fall 1° for every 300 ft. ; this has been always 
acknowledged, and we now see that it is a consequence of the 
more general law which connects temperature and pressure 
throughout the atmosphere. 
Now though we may suppose that A has this value for all in- 
sular climates, yet it cannot have the same value for continental 
climates, on account of the higher temperature of the land ; but 
still there is every reason for supposing that, at any given in- 
stant of time, A is constant for all points in the same vertical 
line ; and when it has been determined from the observed tem- 
peratures and pressures at any two points in that vertical, our 
equa:ion becomes especially adapted for the barometrical mea- 
surement of the distance between them. 
It only remains for me to say that I have already used the 
equation when making a series of observations among the hills 
in the north of England, and always found it true when the 
weather was settled, and sufficient time and care taken in ob- 
taining the mean temperatures of the different strata of air. 
Jamaica MAXWELL HALL 
Larve of Membracis serving as Milk-cattle to a Bra- 
zilian Species of Honey-bees 
THE connection between the ants and the Aphides has long 
since been generally known ; in the proper season we always 
find ants very busy on those trees and plants on which the 
Aphides abound, and if we examine more closely we discover 
that their object in thus attending upon them is to obtain the 
saccharine fluid which they secrete from two setiform tubes 
placed one on each side just above the end of the abdomen, and 
which may well be denominated their milk (Kirby and Spence, 
“ Introduction to Entomology,” 7th edition, p. 335). Ithas also 
long been observed and described, that not only do the Aphides 
yield this repast to the ants, but also the Cocci, and that in the 
tropical regions of India and Brazil, where no Aphides occur, 
the ants milk the larvze of several species of Cercopis and Mem- 
bracis (Kirby and Spence, p. 336; Westwood, ‘* Modern 
Classification of Insects,” II. p. 434). Recently Prof. F, Delpino, 
of Vallombrosa, near Florence, observed the same connection 
Fig. 1.—Lateral view of larva. Fig. 3.—Front view of head of imago. 
between Formica pubescens and Tettigometra virescens (‘* Bolletino 
Entomologico,” anno IV. Settembre 1872). But, as far as I 
know, it has never been observed hitherto that honey-bees also 
nourish themselves by the secretion of certain hemipterous in- 
sects. Hence the following observation, made some months ago 
by my brother, Fritz Miiller (Itajahy, Prov. St. Catherina, 
Brazil) may be worth publishing. 
Among the great number of species of Melipona and Trigona 
which, in the tropical and subtropical regions of America, as is 
known, occupy the place of our hive-bee, there is one small 
species of Trigona which has only once been found by my 
brother on flowers (of Sicyos angulata), and which seems to 
nourish itself in a very strange manner. He once found a multi- 
tude of them spread over the body, already strongly putrifying, of 
a large toad; the interior of the large open mouth of the 
toad was filled with these bees, probably sucking the putrid 
juice of the dead body. On another occasion he saw a great 
Fic. 2.—Lateral view of imago. 
number of the same species of bees in the putrifying intestines 
of ahen. Repeatedly he saw them sucking the juice flowing 
out of trees. 
In consequence of other observations this same species ot 
Trigona is supposed by my brother to suck ihe secretion of the 
larvee of a certain hemipterous insect belonging to the genus 
Membracis, or to a closely allied one. As I do not precisely 
know the name of this supposed milk-cow, I here give the illus- 
tration of its larvae and imago, drawn from specimens sent me 
by my brother. ? 
He found the pedunculi of the flowers of Cassia multijuga 
pretty frequently occupied by societies of larvae of this species 
closely crowded together. Amongst these larvze there was pre- 
sent a great number of the above-mentioned Trigona, marching 
all the day long amongst and upon them. When taken between 
the fingers, the larvae of Membracis immediately emitted a litle 
drop of a limpid fluid from the upward bent tip of their abdo- 
men—probably a sweet fluid, for the sucking of which the larvee 
are visited by the Trigona. 
Unfortunately the specimens of this Trigona, enclosed ina 
letter sent me by brother, arrived here quite broken, so as not 
