Marcu 10, 1923] 
NATURE 
341 

mechanical or thermo-dynamical effects on the super- 
incumbent strata seriously influence the stability of 
organic material within the sediments. Thus it is 
not surprising to find that the United States Geological 
Survey is turning its attention to such possibilities in 
certain areas in the Western States, and a brief paper 
(Bulletin 736-F) dealing with oil accumulation in 
laccolithic domes in the Little Rocky Mountains region 
of Montana (the work of Messrs. A. J. Collier and 
S. H. Cathcart) is one of the first results of this 
inquiry. In the cases described, the uplifts are due 
to intrusions of porphyry, some of which are exposed, 
_ others, in the less denuded tracts of country, being 
still covered by sediments of varying ages, principally 
Upper and Lower Cretaceous. Of the former, the 
Eagle sandstone and the Mowry shale are both pos- 
sible oil-bearing horizons, while the Kootenai forma- 
tion (Lower Cretaceous) is well known to be favour- 
able elsewhere. One or other of these horizons could 
be reached by drilling in at least two pronounced 
domes, the Guinn and the Grouse-Alder domes, 
within the area described, to the south of the Little 
Rocky Mountains. The authors do not of course 
prophesy commercial success for any fields which may 
be opened up here, but they have indicated the most 
likely areas in an otherwise discouraging region, and 
it will be interesting to observe, both from the 
scientific and industrial points of view, the results of 
any trials which may ultimately be made as a con- 
sequence of their report. 
LicHTING In Mrnes.—A striking illustration of the 
value of good illumination in enabling output to be 
increased in industrial operations is afforded by some 
experiments in coal mines described by Messrs. E, 
Farmer, S. Adams, and A. Stephenson in the Journal 
of the National Institute of Industrial Psychology. 
The report of the Miners’ Nystagmus Research Com- 
mittee, issued last year, confirmed the impression that 
this disease is due mainly to inadequate illumination. 
The present research shows how the miner’s work is 
hampered and his output affected by deficient lighting. 
There are two chief drawbacks to most existing 
miners’ lamps, the low illumination afforded and the 
exposure of the filaments, which, in such dark sur- 
roundings, give rise to highly inconvenient after- 
images on the retina. The authors describe a form 
of cylindrical shield which has a useful effect in avoid- 
ing this form of glare, and also give the results of work 
for an eight-hour period with the ordinary standard 
miners’ lamp and with a special “‘ porch-light ”’ giving 
six times as great an illumination. It was shown that 
the improved illumination led to an increase in output 
from 2-47 to 2-83 tons, an increase of 14-57 per cent. 
The experiment serves to show the wide field for 
improvement existing in lighting conditions in coal 
mines and the benefits that might be secured by a 
moderate expenditure on research. 
METEOROLOGY AT SOUTHPORT.—Results of meteoro- 
logical observations at Southport for the year 1921, 
and the annual report of the Fernley Observatory of 
the Corporation of Southport, compiled by the 
meteorologist, Mr. Joseph Baxendell, have recently 
been issued. The report is published in two editions, 
copies being circulated by the Southport Corporation, 
and by the Meteorological Office, Air Ministry. The 
Borough Observatory of Southport is the longest 
municipally-maintained meteorological station in 
the British Isles, observations having continued for 
the past 50 years. Daily, weekly, and monthly 
returns are supplied to the Meteorological Office. 
Much time has been devoted to the comparisons 
involved in the investigations of meteorological 
NO. 2784, VOL. 111] 
periodicities; among the clearly indicated cycles is 
one of 5 years, while a rainfall cycle of 53 years is 
said to be the chief. An appendix gives monthly 
averages, for 10 years, of the amount and duration 
of rainfall under different wind directions. It is 
shown that winds from southerly points are pre- 
eminently those of the rainy quarter. The most 
remarkable year during the half-century’s existence 
of the observatory is stated to be 1921, although in 
the north-west of England it was not so dry as several 
previous years; the total deficiency of 4 inches of 
rainfall was trivial in comparison with the extra- 
ordinary drought over south-eastern England. For 
general fine-weather factors there is no known pre- 
decessor to equal it, the outstanding feature being 
the remarkably high mean atmospheric pressure. 
The underground water-level remained extremely 
low until the substantial winter rains in the latter 
part of December. Taken as a whole, the meteoro- 
logical results will serve well as a guide for observa- 
tions made by other municipal bodies. 
DistANCE THERMOMETERS.—Messrs. Negretti and 
Zambra have introduced a type of distance ther- 
mometer which appears to get over many of the 
difficulties and errors to which such instruments have 
been subject in the past. The new instruments 
depend on the expansion of mercury in a steel bulb 
to which a capillary tube of the required length is 
attached. This tube ends in a coiled Bourdon tube 
with the free end of which the pointer of the instru- 
ment gears directly. The pointer moves over a 
circular dial about 300° of which are occupied by the 
scale. The effect of change of temperature of the 
connecting capillary is eliminated by a wire of invar 
running down the tube and reducing the volume 
of mercury to such an extent that the change of its 
volume with change of temperature is identical with 
the change of volume of the steel tube. The errors 
of such an instrument tested at the National Physical 
Laboratory from 0° to 50° C. at no point of the scale 
exceeded 0-05° C, 
PHOTO-ELASTIC RESEARCH.—In a recent number of 
the Memoirs of the Society of French Civil Engineers 
(Bulletin de juillet-septembre 1922) Prof. E. G. Coker 
gives the text of a lecture, delivered by him last 
summer in Paris, which contains an up-to-date 
account of the method of exploring stresses in struc- 
tures by means of celluloid models examined in 
polarised light, a method which is at present making 
rapid progress both here and on the Continent, and 
bids fair to become indispensable to every scientific 
engineer. Besides giving a sketch of the method 
and its general applications, Prof. Coker obtains new 
and interesting results concerning the testing of 
cement briquettes under tension, and compares the 
standard forms of such test-pieces adopted in Britain 
and France respectively. In particular, he shows 
that the standard briquettes adopted in both countries 
for cement tests lead to a strikingly unequal distribu- 
tion of tensile stress across the middle section of the 
test-piece, and thereby to serious error in the deduced 
tensile strength. He suggests, as the result of photo- 
elastic research, a new shape of standard briquette 
which is free from this defect. Further illustrations 
of the method include. a discussion of contact 
stresses and an investigation of the stresses arising 
from the action of cutting tools, both in the work 
and in the tool itself. This part of the lecture is 
partly a restatement of results previously described 
by the author and Dr. Chakko in the Proceedings 
of the Institution of Mechanical Engineers in April 
1922, but various novel points are introduced. 
