Fepruary 4, 1897 | 
NATURE 
377 
A. DE HEMPTINNE publishes, in the December number of 
the Zeztschraft fiir phystkalische Chemie, an account of an 
attempt to detect some action of the Rontgen rays on chemical 
processes. His results confirm those already obtained by Prof. 
Dixon and Mr, H. B. Baker, and others. The conductivity of 
electrolytes in aqueous solution, the hydrolysis of etherial salts 
by acids, and the combination of chlorine with hydrogen and 
carbon monoxide were studied ; no effect could be detected. 
Solutions of silver nitrate in alcohol, and of mercuric chloride 
and ammonium oxalate in water, which are decomposed by 
light, gave only minute and uncertain traces of change when 
exposed to the Rontgen rays. 
A WRITER in the current number of Blackwood’s Magazine 
gives a prospective account of a trans-Pacific cable. It is 
interesting to find that the coral reefs, which, in the opinion of 
the late Sir John Pender, constituted the chief difficulty in the 
way of the scheme, are not a serious obstacle. Modern sound- 
ings have shown the reefs to lie in well-defined groups, and it 
happens that the ocean expanses between them contain wide 
and uniform depressions, particularly suitable for a cable. The 
article points out that the most favoured route is from Vancouver 
to Fanning Island; Fanning Island to Fiji; Fiji to Norfolk 
Island; and from Norfolk Island in two sections—one to New 
Zealand, and the other to Australia. Fanning Island is of coral 
formation, and is about ten miles long by four miles wide ; it is 
the nearest British possession to Vancouver on the Australian 
route. The article gives an account of the history of the Pacific 
cable scheme, and states its financial aspect. 
THE current number of the Comptes rendus contains a descrip- 
tion of an absolute electrometer intended for measuring small elec- 
tromotive forces (about 1 volt), designed by MM. Pérot et Fabry, 
The instrument consists of an attracted disc electrometer, in 
which the necessary sensitiveness is obtained by greatly re- 
ducing the distance between the plates. The attracting disc 
consists of the plane end of a glass cylinder about 6 cm. in 
diameter and 1 em. high, this height being large compared with 
the distance betweeen the two discs. The attracted disc con- 
sists of a thin circular disc of glass about 7 cm. in diameter, and 
which is virtually an infinite plane. These discs are lightly 
silvered, and their: parallelism adjusted, and their distance 
measured by being traversed normally by a beam of mono- 
chromatic light, which forms interference bands between the 
light which has passed directly through the thin silver coating 
and that which has been reflected an even number of times at 
the silvered surfaces. The electrical attraction is measured by 
comparing the deformation produced in three springs, which 
carry the movable disc by the electrical forces, with that pro- 
duced by a known weight when placed on the movable disc. 
The authors have obtained 070048467 as the mean value of the 
€lectromotive force of a Clark cell at o° in electrostatic measure, 
and, taking the electromotive force in electromagnetic units as 
1°4535 « 10%, the value of v, the ratio of the units obtained is 
@ = 2°9989 x 101”, 
The authors think that in this determination, which they regard 
as simply a preliminary one, the mean error between the different 
measurements is I in 1000. 
A PAPER upon the subject of vertical earth-air electric 
currents was presented to the Philosophical Society of 
Washington by Dr. L. A. Bauer on January 9. Vertical earth- 
air electric currents were first revealed by Dr. Adolf Schmidt, 
of Gotha. In his mathematical analysis of the earth’s magnetic 
field—the most carefully executed analysis up to date—he 
reached the following conclusion: The earth’s total magnetic 
force consists of three parts, viz. (1) the greatest part; this 
is to be referred to causes wz/hzx the earth’s crust, and possesses 
NO. 1423, VOL. 55 | 
a potential. (2) The smallest part, about 1/40 of the entire 
force ; this is due to causes ou/séde of the earth’s crust, and 
likewise possesses a potential. (3) A somewhat larger part 
than the preceding ; this does not possess a potential, and, in 
consequence, points to the existence of vertical electric currents. 
These currents amount, on the average, for the earth’s entire 
surface to one-sixth of an ampere per square kilometre. The 
existence of such currents is indicated by the non-vanishing of 
the line integral of the earth’s horizontal magnetic force 
resolved along a closed curve of the earth’s surface. Gauss 
carried out this test in a special case, and finding the integral 
practically zero, he assumed that the entire force is due toa 
potential. More recently Prof. Riicker applied the same test. 
He found ‘‘ no evidence in favour of the existence of vertical 
currents” over a region of the earth—the British Isles—which 
had been very minutely surveyed. The results of some 
preliminary investigations being confirmatory of Schmidt’s 
conclusion, Dr. Bauer determined to carry out the test in a 
thoroughly systematic manner, viz. to take as the closed curves 
parallels of latitude. The results obtained confirm those of Dr. 
Schmidt’s more elaborate investigation. Summing-up, Dr. 
Bauer finds that :—‘‘ There are vertical electric currents which 
pass from the air into the earth, and back again into the air. 
Between 60° N. and 60° S. the average current intensity per 
square kilometre is about one-tenth of an ampere.” 
Ar Governor's Island, a few days ago, Lieut. Hugh D. 
Wise, of the United States Army, made a very successful ascent 
by kites. He used four kites, a modification of the Hargrave 
invention, and weighing about 16 pounds each. The kites 
were attached to a windlass running out a }-inch manilla cord 
connected with an iron ring drawn up fifty feet above the 
ground. From the ring the kites ran up on two I-inch cords. 
Two kites, one above the other, were attached to each of the 
latter cords. To the ring was also attached a tackle and block, 
running a heavy rope to the ground. On this rope Lieut. 
Wise was drawn up, and remained for a considerable time at a 
height of about 42 feet, surveying the environment on all sides 
with his field-glass. The wind was blowing fifteen miles an 
hour, and the pull of the kites was about 400 pounds. 
A sHoRT but interesting account of the earthquake of last 
December 17, founded partly on newspaper descriptions and 
partly on the notes of observers, is given in Symons’s Aefeoro- 
logical Magazine for January. The first of the two maps, which 
illustrate the paper, shows many of the places where the shock 
was felt and where structural damage occurred. The writer 
remarks that the area affected was apparently 350 miles in dia- 
meter, and contained about 100,000 square miles ; and that the 
part within which damage was produced, which is nearly central 
with regard to the former, is about 130 miles from north to 
south, and of a maximum breadth of 40 miles, thus containing 
nearly 4000 square miles, or about ten times the corresponding 
area of the Essex earthquake of 1884. He believes that there 
is evidence that the shock was one of a series which can be 
traced back for more than six centuries, and gives small sketch- 
maps showing the approximate boundaries of the shocks of the 
years 1248, 1574, 1705, 1863, 1868, and 1896. Taking the 
initial time of the recent disturbance as 5.32 a.m., and Hereford 
as the centre, the more careful time records appear to show that 
the velocity of the earth-wave may have been about 30 miles a 
minute. The paper concludes with a list of the minor shocks, a 
series of records of the luminous phenomena, which, it is sug- 
gested, prove only that a local thunderstorm occurred at about 
the same time as the shock, and some references to the sound 
which accompanied the earthquake. 
DuRInG the last few years, one of the principal sources of 
income of cold-storage companies in the United States has been 
