158 
NATURE 
[JUNE 12, 1902 
Mimicry in Insects,” illustrated by lantern-slides in natural 
colours; a discussion on the measures to be adopted for the 
preservation of our indigenous flora was initiated by Prof. 
Boulger and Mr, E. A. Martin ; and papers on ‘‘ Well-sections,” 
by Mr. Whitaker, and on ‘* Eolithic Flint Implements,” by Mr. 
E. R. Harrison, were taken as read, but will appear in Zhe 
South-Eastern Naturalist for 1902. The event of the meeting, 
however, was the address by the president, Dr. Jonathan 
Hutchinson, F.R.S., on leprosy, with special reference to its 
antiquarian aspects, with reasoned argument against the 
theory of contagion. The congress was held, by permission of 
the governors, in the Simon Langton Schools, where an ex- 
cellent local museum had been got together, including marine 
aquaria exhibited by Mr. Saunders, Mr. Harrison’s eoliths, and 
many fresh specimens of the British orchids, so well represented 
in the district. The members visited the Cathedral, and were 
entertained at the deanery by the Dean and Mrs. Farrar, and 
were also received, on the Friday evening, by the Mayor and 
Maycress. The congress terminated on the Saturday afternoon 
in a visit to the South-Eastern Agricultural College, Wye, at the 
invitation of the principal, Prof. A. D. Hall, where the 
members were shown over the farms and laboratories by the 
staff of the college. 
A curious effect produced by lightning is described to us by 
Dr. Enfield, writing from Jefferson, Iowa, U.S. A house 
which he visited was struck by lightning so that much damage 
was done. After the occurrence, a pile of dinner plates, twelve 
in number, was found to have every other plate broken, It 
would seem as if the plates constituted a condenser under the 
intensely electrified condition of the atmosphere. The par- 
ticulars are, however, so meagre that it is difficult to decide 
whether the phenomenon was electrical or merely mechanical. 
A REPORT upon a Bill for the adoption of the metric system 
of weights and measures in the United States was recently sub- 
mitted to the U.S. House of Representatives by the Committee 
on Coinage, Weights and Measures. The report recommends 
strongly that the Bill be passed and the use of the system made 
compulsory because of itsinternational character, educational bene- 
fits andcommercial advantages. The scientific world to-day enjoys 
the advantages of a universal system of weights and measures, 
and this fact has doubtless facilitated .the development and 
spread of natural knowledge. With regard to the introduction 
of the system into a country, the experience of other nations has 
shown that the confusion and inconvenience caused by a change 
in the measures used in daily life are largely over-estimated. 
Finally, the committee remarks :—‘‘ It should be kept in mind 
that the metric system is just as capable of a binary subdivision 
as any other, although the advantages of such a division are 
only apparent in the most ordinary business transactions and for 
the first few subdivisions, After the adoption of the metric 
system, the use of the half and quarter metre and half and 
quarter kilogramme would be as common as our half and quarter 
dollar—smaller quantities would be expressed in decimals pre- 
cisely the same as in the case of our money, In 1866, 
Congress legalised the metric system, From that time on it has 
been growing in favour and in practical use, It is here to stay, 
not only in scientific work, but in commerce and manufacturing. 
It is now used by about two-thirds of the people of the world. 
. Your committee believe the time has come for the gradual 
retirement of our confusing, illogical, irrational system and the 
substitution of something better. The first step in this direction 
should be the introduction of the metric weights and measures 
into the departments of the Government. The use of these 
weights and measures will simplify their work. It will 
familiarise the people with them and encourage their application 
to the common affairs of life. Your committee have no doubt 
NO. 1702, VOL. 66] 
that the benefits to be derived will far more than compensate 
for such inconvenience and expense as may be involved in the 
change.” 
EXPERIMENTS with a system of wireless telephony are being 
carried out (according to the Scéentific American) in America 
by Mr. Stubblefield. The results so far have been of a promising 
nature, conversation having been successfully transmitted over 
several hundred yards on land and several hundred feet on 
water. The system used is an earth-conduction one, and is, 
therefore, similar in principle to, though doubtless differing in 
detail from, many other wireless telephony systems which are 
being tried in various countries. We have had occasion to 
comment on these in NATURE from time to time during the 
past year. It cannot be said that the results which have as yet 
been obtained by any of the experimenters are of sufficiently 
striking value to justify the prediction of a great future before 
this method of communication. But it is evident that many 
inventors are attacking the problem, and it is likely, therefore, 
that something of practical utility may be developed by their 
efforts. It is easy to conceive of many circumstances in 
which an earth-conduction telephonic system, even of limited 
range, would be very valuable. 
A PAPER on the accuracy of an improved form of silver 
voltameter, by Messrs. T. W. Richards and G. W. Heimrod, is 
published in the Proceedings of the American Academy of Arts 
and Sciences for April. The silver anode is suspended in 
a porous pot, which is itself hung inside the platinum crucible 
serving as kathode. The level of the nitrate solution inside the 
porous pot is kept slightly lower than that outside, and thus 
outward filtration of the anode liquid is prevented. The 
authors not only examined the accuracy of the voltameter, but 
made a valuable investigation of the effects of the various im- 
purities likely to result from irregularities in the electrolysis or 
anode. Asa result of this, and from the data furnished by the 
experiments with the porous pot voltameter, corrections are 
deduced for the determinations of the electrochemical equivalent 
of silver made by Lord Rayleigh and Mrs. Sidgwick, F. and 
W. Kohlrausch, Kahle, and Patterson and Guthe respectively. 
The corrected figures give a mean result of 0°0011175, none of 
the four individual values differing from this by more than 
002 per cent. Hence the number of coulombs associated with 
one gram-equivalent of any electrolyte is 96,580. 
A PAPER on the sensitiveness of the coherer, by E. R. Wol- 
cott, appears in No. 51 of the Bulletin of the University of 
Wisconsin. The experiments were carried out with coherers of 
two pieces of metal in light contact, as it was found that these 
gave more consistent results than ‘‘filings”” coherers. Different 
metals were tried, and also the effect of coating different metals 
with a film of the same substance, such as collodion, The 
author concludes that both the metal and the coating affect 
the sensitiveness. Aluminium was found to be the most 
regular in response, but nickel showed the lowest critica) 
potential, that is to say, responded to the least energy ; 
this probably accounts for its value in long-distance wireless 
telegraphy. The author examines his results with reference to 
the theories of the coherer’s action put forward by Branly, 
Lodge, Bose, and Guthe and Trowbridge. Guthe and Trow- 
bridge’s theory explains more of the phenomena than do any 
of the others, though all the observed facts are admissible 
on Lodge’s theory. Some of the facts, it is said, are in dis- 
agreement with the theories advanced by Branly ard Bose. 
Dr. C. DIENER contributes to the Jahrbuch der k.-k. geol. 
Reichsanstalt (Band li. Heft 2) an appreciative article dealing 
with the scientific work of Albrecht von jKrafft, whose untimely 
