476 
POPULAR SCIENCE REVIEW. 
Wm. Thomson’s self-recording apparatus, specimens of the'photographic 
curves thus taken being exhibited at the meeting. The Windsor observa- 
tions, taken by Dr. Everett with apparatus of a different kind, also invented 
by Sir Wm. Thomson, but not self-recording, extended from October 1862 
to August 1864. Monthly averages which had been taken showed that at 
Kew there had in every month been two maxima in the day — one of them 
between eight and ten A.M., and the other, which was more considerable, 
between eight and ten p.m. At Windsor, on the contrary, the electricity 
between eight and ten p.m. had in every month been weaker than either 
between eight and ten a.m. or between two and three p.m. The annual 
curve for Kew had its principal maximum in November, and another in 
February or March. At Windsor the principal maximum was in February 
or March, and the minimum in June and November. The annual curves for 
the two places agreed pretty well from January to October, but were curved 
in opposite directions from October to January. 
A New Test for Ozone . — In the Comptes Rendus for July, Admiral Berigny 
records numerous experiments upon the correct methods of detecting ozone 
in the atmosphere, and states that he has found protoxide of thallium the 
most delicate test. While, for example, ordinary oxygen produces little 
effect on papers saturated with solution of this substance, ozone instantly 
reveals its presence by giving a brown tint to the paper. Unfortunately, 
li owever, for the practical usefulness of the new test, it is found that car- 
bonic acid affects the protoxide of thallium in the same manner as ozone. 
Hence, the discovery has little more than a purely theoretical value. 
Relation of Ozone to Direction of Wind . — The results arrived at by obser- 
vations made at sea by Mr. W. F. Moffat, B.N., and reported by Dr. 
Moffat to the British Association, are very remarkable. It was found that 
as the wind veered with increasing readings of the barometer from south 
points of the compass through W. to N., ozone disappeared, and continued 
absent while the wind was in points between N. and E., and that it re- 
appeared as the wind veered with decreasing readings of the barometer to 
S. points. The disappearance and reappearance of ozone with those con- 
ditions were so regular, that the changes appeared to be the result of an 
invariable atmospheric law, and Mr. Moffat was induced to examine the law 
of rotation of the wind, so clearly developed by Dove, and the results of the 
examination led him to believe that the polar current is the non-ozoniferous, 
or that of minimum of ozone, and that the equatorial is the ozoniferous, or 
that of the maximum of ozone. According to the rotation theory, the N. 
polar current forms the N.E. “ Trade,” and the S. polar the S.E. “ Trade,” 
while the equatorials form the northern and southern hemispheres to upper 
or returning “ Trades.” These returning “Trades ” come to the earth’s 
surface in the northern and southern hemispheres about the 28° or 30° 
of latitude — the latitude varies with the season — N. and S. of the equator. 
If these deductions are to be relied upon, the N.E. and S.E . 11 Trades ” ought 
to be the minimum of ozone currents, and the returning (t Trades” the 
maximum of ozone currents, the one in the northern hemisphere forming 
the S.W. wind, and the other in the southern hemisphere a N.W. wind. 
