August 19, 1886] 
NATURE 
361 
logical security than it has ever occupied before. Far, then, 
from joining the ‘‘ contention” of my critic in seeking to depose 
natural selection as a theory of the genesis of adaptive structures 
and instincts, I have expressly sought to fortify that theory as a 
**mechanical” explanation of these phenomena. Whether or 
not I have been successful I must leave others to judge, after 
they have done me the justice to read my original paper. But, 
be this as it may, the ambiguity of that paper must indeed be 
extraordinary, if it leads any one to suppose that my argument 
is precisely the opposite of what it is intended to be. 
Geanies, Ross-shire, August 16 GEORGE J. ROMANES 
Meteorology and Colliery Explosions 
THE catastrophe at Woodend Colliery on Friday last again 
directs attention to the connection generally believed to exist 
between explosions of fire-damp and atmospheric changes. The 
real nature of this connection is but little, if at all, understood. 
From time to time observations have been taken with the view 
of throwing some light on the subject, but as the observations in 
one mine were discussed without reference to what may have 
been occurring in other districts, the results have not added 
much to our knowledge. Meteorology, however, is now suffi- 
ciently advanced to permit the adoption of another and more 
satisfactory method of dealing with the question. 
The idea so long prevalent that certain fixed points on the 
barometric scale indicated certain kinds of weather has now 
been discarded, the examination of synchronous weather charts 
showing conclusively that the weather changes are not so much 
dependent upon the height of the barometer at any one place as 
upon the relations existing between readings over a tract of 
country ; the direction in which the highest and lowest readings 
lie, and the difference of pressure (the barometric gradient) 
between neighbouring places—these form the basis of our modern 
weather knowledge. Nothing of this kind has hitherto been 
attempted when dealing with observations from collieries. If 
the presence of gas in mines is in any way regulated by changes 
of atmospheric pressure, it would be well to see if, like the 
weather, it is distributed in areas, and whether in these areas 
again some localities would have more gas than others, de- 
pendent more upon the distribution of pressure than upon local 
readings. With the object of discovering some law or laws 
governing the presence of gas, I appeal to colliery officials in 
every coal-field in Great Britain and Ireland to supply me with 
the few observations detailed below for a period of four months 
—from September 1 to December 31, the best part of the 
year for such work. 
The Meteorological Office Weather Charts issued daily (Sun- 
days included) at 8 a.m. and 6 p.m. show the distribution of 
pressure, winds, temperature, and weather. To these I propose 
adding the information supplied from mines af the same hours. 
Those who cannot arrange for two observations daily, to give 
preference to the morning set. The gas observation being the 
most important, I would be glad if precise information can be 
given. Absolute uniformity cannot be expected, but I would 
suggest that, where possible, a disused gallery favourable to the 
object in view should be us2d, one where the changes in the 
quantity of gas can be stated in yards or feet, thus turning the 
gallery into a gas barometer somewhat similar to the one at 
Seaham Colliery after the explosion of a few years ago. Those 
who have not the facilities for such measurements can still give 
valuable data if they do no more than note the increase or 
decrease of gas as ‘‘slight,” ‘‘ moderate,” or ‘‘great.’’ The 
appended specimen of the form for recording the observations 
Form for Recording Observations 
ah SOB OEB OREO Colllienyanedrgrs.ieceesseenesccs 
‘Top of shaft, In underground workings, 
ooeent ice spore see yards from shaft 
Tats sea-level | ...... feet below pit-bank Gasin 
peptember, = gallery, | Remarks 
1886 Tempe- | Q yards 
rature Baro- | Tempe- |. "80 
in the |Weather meter aie mayokaw 
shade passing 
1st, 8 a.m. 
6 p.m 
2nd, 8 a.m. 
6 p.m 
has columns for the air-temperature in the shade’ at the pit-bank, 
and the weather ; while underground, in addition to the gas- 
record, the reading of a barometer and thermometer, and quan- 
tity of air passing at a fixed point some distance in the workings ; 
also, remarks on the variations of the gas and ventilation at 
other than the regular hours. A sheet of close-ruled foolscap, 
arranged as indicated, will contain the data for one month, and, 
as soon as filled up, should be forwarded to me at the Meteoro- 
logical Office, London, S.W. On the back of the first return 
particulars are required of the geographical position of the 
mine, the name and address of the manager, whether the baro- 
meter is a mercurial or an aneroid, together with the readings 
of the same at the pit-bank at 8 a.m. daily for a week before 
} taking it underground, and ‘describing the plan adopted in 
measuring the gas. It must be understood that I am under- 
taking the discussion as my own work, for which the Meteoro- 
logical Council is not responsible. Hy. HARRIES 
August 16 
Railway Weather Signals 
WITH reference to the notice given in NATURE, vol. xxxiv. 
Pp: 347; of the ingenious plan adopted by the Norwegian Meteoro- 
logical Institute for disseminating its weather reports, it may not 
be known to all of your readers that a similar system of signals 
has been in use for some time on the railroads in Ohio, Penn- 
sylvania, and Canada. The day signals there consist of sheet- 
iron disks about three feet in diameter, and are displayed on the 
side of baggage-cars. The signals are shaped like the sun, a 
crescent, or a star, and differ in colour, being red or blue. The 
red colour refers to the temperature, and the blue to the state of 
the weather, as rainfall or snow. This system of signals was 
first brought into practical operation by Prof. T. C. Mendenhall, 
Chief of the Ohio Meteorological Bureau. 
A system of night-signals for railways is also under trial in 
Pennsylvania: they are in the form of rockets or an exploding 
cartridge, which, when fired, may be seen from six to ten 
miles. Cuas. HARDING 
August 17 
Tornaria and Actinotrocha of the British Coasts 
THREE species of Balanoglossus are known to occur on the 
shores of North-West Europe. . Balanoglossus kupfferi was taken 
by Willemoes Suhm at Helleback, in the Sound, that is, on the 
coast of Zealand (Zeit. f. wiss. Zool. vol. xxi. 1871); Balano- 
glossus salmoneus, Giard, and B, vebinii occur, according to Mr. 
Bateson’s last paper in the Quarterly Fournal of Microscopical 
Science, at Concarneau, in’ Finistére, and I believe also at the 
Channel Islands. But no Balanoglossus has yet been found on the 
shores of Britain. It will therefore be of some interest to British 
naturalists to learn that in August 1884 I obtained in the tow- 
net a larva which seemed to possess the distinctive characters of 
Tornaria. I had not leisure at the time to study the specimen 
with much attention, but I made a hurried sketch of it, which 
shows the presence of two parallel longitudinal bands of cilia 
anteriorly, and a single transverse band posteriorly. At the 
posterior end is a conical protv berance resembling the adhesive 
organ described by Bateson in his creeping larva. The position 
of the mouth was not ascertained, but was probably between the 
two anterior bands of cilia. The water vessel and tuft of cilia 
at the apex of the preoral lobe were not observed. This larva 
may not have been Tornaria, but I think it really was that form ; 
and naturalists who are spending an autumn holiday at the sea- 
side would probably, if they undertook the search, succeed in 
finding Balanoglossus in the littoral sands, and its larvee in the 
shore waters. 
Phorenis is also at present, I believe, excluded from the British 
littoral fauna, but is certainly present on our shores, though 
no adult specimens have been taken. I took large numbers of 
Actinotrocha in the tow-net, close to the shore, in September 
1883, a little to the north of the mouth of the Cromarty Firth. 
If I am mistaken in supposing that adult Phorenis and Balano- 
glossus have never been found on the coast of Britain, I shall be 
glad to be corrected. J. T. CUNNINGHAM 
Mock Suns 
As I observe the omission from my letter on the pazhelia or 
mock suns of last month (p. 313) of the diagram which was 
