208 

passes being heated and illuminated by the comet ; and that the 
other phenomena are also due to the ether, 
I rely that you will do me the justice to allow space for me to 
remind your readers that the theories which Prof. Reynolds so 
emphatically calls /’s, were propounded and published by me 
sixteen years ago, and noticed by most of the press throughout 
the world. 
The following quotation from my pamphlet (now out of print) 
will enable your readers to judge of the correctness of these 
statements :— 
“‘It was noticed, in reference to ‘ Biela’s comets,’ that the 
smaller one, which I call the éer¢iary comet, and which travelled 
in a separate or distinct orbit, that a kind of vei, or stream of 
light, joined the two heads, the stream of light being /arger as it 
approached the head of the /avger comet. This stream of light, 
I think, proves most satisfactorily that the ‘tails’ of comets are 
nothing more than the illuminated or heated medium through 
which the comets pass. The cy/éndrical appearance which these 
‘tails’ sometimes present, I believe is occasioned by the vocary 
motion of the comets (or infant worlds) on their respective axes. 
The increased number of ‘tails’ to a comet is occasioned by the 
interposition of one or more secondary or tertiary comets, inter- 
cepting the ‘tail’ of the superior body, the direction of which 
‘tails’ would be determined by the position of the said inter- 
cepting bodies, aod the variety of affearance in connection with 
the point from which they were viewed,” &c. 
Bayswater, Jan. 9 J. BEprorD, Ph.D. 
The Artificial Introduction of Plants 
THE remarks on page 142 of your number of December 22, on 
the proposal of the Manchester Field Club to introduce plants 
foreign to the district, ought to be printed in red_ letters. 
The geographical distribution of plants is not the least interest- 
ing branch of botanical study, and is, besides, important in its 
bearings upon other natural sciences, such as geology and 
meteorology, and as such has formed the subject of laborious and 
intelligent research among various eminent naturalists. 
Amateur botanists can carry on their favourite pursuit in two 
widely-different ways: they can play at science, and so amuse 
themselves to their own satisfaction, may be, but with little 
advantage to what they propose to admire, or they may patiently 
and conscientiously work and observe within their own sphere of 
research, and thus be able to render, as occasion serves, very real 
service to science at large, more, perhaps, than they are aware 
of at the time, and certainly to earn very genuine pleasure for 
themselves. 
Not that I mean to insinuate that the Manchester Club are 
playing at science, but I warmly agree with your remarks that a 
mistake is being made by them in this respect. The instance is 
not a solitary one, even in my limited experience. Not long ago 
I found myself protesting against the notion of an amateur 
botanist (in England), who was endeavouring to introduce a 
species into a new locality. This is about as detrimental a pro- 
ceeding in its way as that of the wanton eradication of a species 
from a neighbourhood. 
I write con amore, for I happen to live and botanise in a part 
of Europe lying off the line of railways, therefore little visited, 
but possessing an interesting and somewhat peculiar flora, and 
am not unfrequently applied to by eminent botanists for informa- 
tion as to the real existence in the district of plants alleged with 
more or less of truth to be indigenous here. 
Fiume, Austria AN AMATEUR BOTANIST 
Science Teaching 
JN an article in NATURE, December 29, 1870, on ‘‘Science 
at School Boards,” the teaching capabilities of this country ap- 
pear to me to be under-rated ; I refer especially to the following 
passage :—‘‘ We would advise that some attempt be made to 
teach some quantum of Natural Science somehow. The present 
masters will probably be utterly ignorant of any branch of 
Science!” 
If such is the fact, I would ask what have the training-schools 
been doing for years past ? Most of these schools have university 
men as teachers, or men who have obtained a lectureship ; and 
surely they have tumed out students of two years’ residence, 
capable of teaching one or more of the elementary branches 
named by the writer of the article referred to, 
NATURE 



| Fan, 12, 1871 
Does Dr. Lankester really think that the majority of the 
trained certificated masters of this country are incompetent to 
teach elementary physical geography? Many of these masters 
possess, I believe, a certificate for teaching Science, in virtue of 
having passed an examination under the Science and Art De- 
partment ; and surely the examiners employed by the Depart- 
ment are such men as even Dr. Lankester would not ignore. 
I feel confident that so far as teachers are concerned the matter is 
not so bad as Dr. Lankester imagines. The Revised Code checked 
all science teaching in elementary schools, but only let the Com- 
mittee of Council accede to the appeal now made, and they will 
find plenty of masters able and desirous of teaching the elements 
of Science in our elementary schools. 
There are two obstacles to be overcome before good results 
can be obtained. There must be better and ampler teaching 
power employed in our schools, so as to give the master the op- 
portunity to carry out consecutive teaching ; and then people 
generally must be made aware of the importance of Science to the 
artizan class, parents must be taught to appreciate the efforts made 
for their children. I will venture to say that more than half the 
work of the best teachers of this country is neutralised by the in- 
difference or ignorance of parents. 
Wisbech, Jan 3 SAMUEL H. MILLER 

The Frost 
? 
I REMARK in the ‘‘ Notes” of your last number, it is stated 
that ‘‘the lowest temperature at Blackheath was 15°3° F., on 
the night of the 24th December.” 
Now, assuming the correctness of the instrument from which 
this observation was taken, the locality must be much more pro- 
tected from frost than that in which I reside. I have two good 
registering thermometers placed in a N.E. aspect, at about 
twenty-five or thirty feet from the ground—the one an upright 
mercury (Beck, Cornhill), the other a horizontal spirit tube 
(Hughes, Fenchurch Street), and the readings, which corre- 
spond exactly, were as follows :— 
On the night of 23-24 Dec. 12° F., and at 7 A.M. on the 24th 
14°. The maximum temperature (about noon) on the 24th was 
24°, and at 11 P.M. the mercury had dropped to 16°. 
On the night of the 24-25th the minimum was 9° F., at which 
point the register stood as late as 7 A.M. on the 25th, and even 
at 10 A.M. it had only risen 1° (10° F.) 
I send you these observations, which I believe to be very 
correct, as they may be of some interest to meteorologists in our 
neighbourhood. 
Blackheath, Jan. 9 JOHN CAREY 
[It will be seen that these figures correspond very nearly with 
those given in our ‘‘ Notes” this week.—ED. ] 
On Sunday morning, Ist inst., a standard terrestrial radiation 
thermometer (exposed here on the previous evening) registered 
the unusual low temperature of 6°3 °F’, or 25°7° below the freezing 
point. 
The instrument was placed a few inches above snow covered 
grass on a gravelly soil, and exposed to nearly the whole sky. 
JOHN JAMES HALL 
Temporary Meteorological Observatory, 
Fulwell, Twickenham, Jan 5 

Sharks announcing their own Capture 
Ligut. C. H. Taytor, of H.M.S. Cossack, in his Remark- 
book for 1869-70, alludes to the following ingenious mode of 
making sharks announce their own capture, It appears that the 
island of Johanna, at the north end of the Mozambique Channel, 
is frequently visited by numerous sharks, whose flesh is esteemed 
as an article of food by the natives, who also prize the skin and 
oil for domestic or commercial purposes. 
The Johanna men, however, being too lazy to fish in what might 
be termed a legitimate manner, have recourse to floating traps, 
with line, hook, and bait, and supporting above water a pole and 
basket. A bight of the line near the raft is attached to a bolt or 
toggle, which, when in place, keeps the pole in an upright 
position, but the moment a strain is breught on the line by the 
fish being hooked, the toggle is withdrawn, causing the pole and 
basket to fall, which is a signal to the people on shore that the 
prey awaits their coming. G, F, McDouGa.Li 
Hydrographic Office, Admiralty 


Ft 
