That the cultivation of ipecacuanha should be taken up at 
Edinburgh is nothing more than might reasonably be demanded 
of a garden maintained at the national expense. It was indeed 
an arrangement which the residence at Edinburgh of Dr. 
Anderson, the then Superintendent of the Calcutta Botanic 
Garden, who was home on sick leave, rendered eminently de- 
sirable, and one upon which I was fully consulted by the Govern- 
ment, as appears in Dr. Anderson’s report already quoted. Nor, 
in reference to the subject, should it in fairness be suppressed, 
that not only has the successful introduction of the ipecacuanha 
into India been due to the establishment at Kew, but that Kew 
has at the same time supplied living plants to Ceylon, the Mau- 
ritius, Jamaica, Trinidad, Barbadoes, Queensland, and various 
home and continental gardens. 
Prof. Owen again appears to have been completely misinformed 
in respect to Welwitschia, which, he implies, had been sent 
to Kew in a state fit for cultivation. A very large and old spe- 
cimen with the tap-root chopped off before its arrival, was 
placed for convenience in a pot of earth, and exhibited in the 
succulent house, where it would be likely to attract much atten- 
tion, and would also be in contiguity to other plants from the 
same region. This was done without the slightest expectation 
of its showing any disposition to grow, and solely to gratify the 
public curiosity. On the appearance of symptoms of decay 
from the dampness incidental to a greenhouse, it was at once 
transferred to the museum, where it now remains. Prof. Owen, 
apparently quoting a statement in my memoir on Welwitschia, 
pointedly alludes to the fact that ‘‘cones with ripe seeds” had 
been received at Kew, but he omits to give the following words, 
“the albumen of which was perfectly rotten;” and when 
alluding to my acknowledgment of the receipt of ‘‘ fine young 
plants,” he does not add that these were Dr. Weliwitsch’s speci- 
mens gathered years before. 
Prof. Owen refers to my answer to Q. 6,661 in the evidence 
given before the Royal Commission, as having by groundless in- 
sinuation ‘‘inflicted pain on fellow-servants of the State and 
collaborators in science, on men at least his (my) equals, and 
one of whom in a recondite botanical problem has shown him- 
self his (my) superior.” As Prof. Owen does not quote this 
question and answer, I shall do so. They are as follows :— 
Q. 6,661.—‘‘ Has there been insufficient space in the British 
Museum for the reception of specimens for the enlargement of 
its herbaria, or has any other obstacle interfered? ””—A. “‘ With 
regard to the British Museum I do not think any person can 
answer that except the officers of the establishment. I do not 
think that the nature and extent of its botanical collections or 
their condition is well known except to its officers.” 
I leave it to the reader to say whether any possible insinuation 
could be conveyed in such an answer, and, being unconscious of 
any, shall conclude with expressing my conviction that here again 
Prof, Owen has been misinformed. J. D. Hooxer 
Royal Gardens, Kew, Noy. 15 
The Diathermacy of Flame 
I HAVE to thank Lord Rosse for pointing out an omission in 
my communication on this subject. It was not, however, an 
‘oversight,’ as Lord Rosse supposes, the source of error in 
question having been duly considered, and its amount calculated, 
when the experiments were made. It was neglected on account 
of its smallness, As its theoretical importance is unquestionable, 
and the amount of experimental error is likely to be much over- 
rated, I gladly supply the following figures, which show that 
this source of error was fairly negligible. 
As heat, like all other radiant forces, necessarily diffuses with 
the square of the distance from its source, my method of main- 
taining a constant mean distance by lighting an equal number of 
jets equidistant from each side of the middle flame, was liable to 
an error equal to the difference between the square of the dis- 
ance of the middle flame from the thermometer and the mean 
of the squares of the distances of the other flames. The fiz 
were } of an inch apart, and the middle flame was 14 in, dis 
from the thermometer. Thus, in the first trial, when only th 
flames were lighted, the distance of the nearest was 13¢ in., of 
the middle 14in., and of the farthest 14}in. Taking } in. as 
our unit, the middle flame was 56 distant, the nearest 55, and, 
the farthest 57. 56” = 3136, 55? = 3025, and 57? = 3249 
The mean of 3025 and 3249 is 3137, instead of 3136 as ex 
mentally assumed; the error tin this case is thus only a 
. a 
Deri- 
1 
74°25, 
of a degree, a quantity far too small for consideration in using 
common laboratory thermometer reading only to half degrees, 
Proceeding onwards, the error of course continued incre 
until it reached its maximum, when the 1st and 17th jet , 
lighted. The 1st was 48 quarter inches distant from th ;. 
thermometer, the 17th was 62, 48?=2304, 627=3844. The 
mean of these is 3074, instead of the experimentally assumed 
mean of 56°=3136. The difference is 62, i.e. re ip 
the last increment of heat. Thus the maximum error was less. 
than /'5 of a degreee, and the mean error lies between this and 
of a degree. ; 
of the 4° increase which my thermometer registered, or 
I 
784°25 i 
As regards the last paragraph of Lord Rosse’s letter, I 
would suggest that, with gas passing through a given orifi an 
the passage of equal quantities neccessarily implies equal 
pressure ; that in turning the micrometer screw of the sup- 
ply tap so as to cause each additional pair of equal jets to 
consume an equal additional quantity of gas, I was merely 
admitting into the space between the tap and the jets a quantity 
of gas just sufficient to maintain an equal elastic tension or 
pressure in spite of the varying quantity issuing from the jets. 3 
W. Marttieu WILLIAMS — 
Skeletons of Wild Animals 
Mr. CLARK, of Cambridge, in Nature of Oct. 31, remarks 
on the general absence of skeletons, especially those of the Felidae, 
in museums, and states that, so far as he knows, no European — 
museum possesses more than skulls. It is with pleasure, there- 
fore, that I draw his attention to the fact of the existence of a 
perfect skeleton of thejlion in the Ipswich Museum. Besides this, 
there is a skeleton of the mole, one of the dog-faced monkey 
(Cynocephalus anubis), one of the dolphin, two very finely pre- — 
pared skeletons of the boa constrictor, besides others of the 
ostrich, &c, J. E. Taytor 
Treble Rainbow ¥ 
Anour the middle of August, whilst standing on platform of 
the station at Exmouth, I witnessed a phenomenon which I a 
think is rare enough,to be worthy of record. The sun was about. 
an hour off the western horizon, and the river, which is to the 
west of the station, and is in that part about a mile and a-half 
broad, was perfectly calm ; but there must have been a breeze 
blowing overhead, for a heavy shower of rain came rapidly up 
from the westward, and when it had passed to leeward displayed 
the two ordinary rainbows brightly ; and not only these, for 
between them appeared the arcs of a third bow cutting the other — 
two, the inner one on the horizon and the outer about ten d 
or thereabouts above it. This third rainbow appeared to 
its centre as much above as that of the ordinary rainbow was — 
below the horizon, and was due to the reflection of the sun from 
the calm surface of the river. The arcs of the third rainbow ex- 
tended but a very small distance beyond the secondary bow, but 
were bright enough at the intersection to show a sort of check- 
work of colours, which presented a most curious appearance. 
Oxford, Nov. 5 A. Mattock ~ 
Circular Spraybows 
THERE have been several accounts lately in NATURE of circular _ 
rainbows, but none of your correspondents have mentioned q 
“ circular spraybows ;” of course, in themselves they are of no 
great value, but under certain circumstances they can be seen. 
so near that their brilliancy exceeds that of a rainbow, 
The most perfect which I have seen was at the Falls of Foyers, — 
off Loch-ness, at 8 A.M. on September 1, 1868, The previous" 
