168 
geology and others, and yet it will fre- 
quently be necessary for him to consult the 
cards in these subjects : 
Wherein do 0330 and 0335 differ from 3205 and 
3210? | 
Why a special section for 0345 after all the other 
discussions of elasticity? Compare 0360 and 1520. 
0365, too comprehensive, should be sub-divided. 
Why the sub-head Hardness, Friction and Vis- 
cosity ? 
Compare 0420 and 0550-0555-0560. 
Why no conductivity of gases after 1430 ? 
Is not 1450 superfluous ; also 1580 ? 
In 1710 and 1720 the use of ‘ thermal’ seems am- 
biguous and ill advised. 
Compare 1720 and 5140. 
2040, superfluous. 
2120 and 2210 are conflicting, and why should col- 
loids be put in 2120? 
2330 should be considerably sub-divided. 
Is 3020 necessary ? 
3120, compare 3320. 
3160 is sure to conflict with the sub-head ‘ inter- 
ference and diffraction.’ 
3210 and 3215 should at least refer to 0330 and 
0335. 
3220 and 3225 parallel 3255. 
3240 at least partly covers 3260. 
3320 and 3120 interfere. 
3320 quality and 3330 should go to ‘sound’ in- 
stead of ‘sensation’ and the ‘voice’ including 
‘articulation ’ and ‘ phonetics’ should have a special 
head. 
It would seem possible to improve 4000 to 4040. 
5090 and 5240 conflict. 
5130 and 5230 conflict. 
5020 and ‘reflexion and refraction’ will lead to 
confusion. 
Why is anomalous dispersion in 5350? 
5460, pressure and Zeeman effect should be included. 
5550, where are any reference to color, color theorieg 
and the optics of the eye? At least a reference must 
appear here. 
6010, too brief, should have several sub-heads. As 
“Ampére,’ ‘Ohm,’ ‘Farad,’ ‘induction,’ magnetic 
quantities, ete. 
6130 and 6140 should be under 6010. 
6240 are too comprehensive. 
6305, primary and secondary should be separated. 
6315 belongs under 6010. 
6330, ambiguous. 
6350 and 6355, much too comprehensive, each should 
be sub-divided in three. 
6560, same comment. 
6110 and 
SCIENCE. 
[N. S. Vou. X. No. 241. 
6570, where are electrostatic waves ? 
6580, what is electro-optics ? Have these phenom- 
ena not been given elsewhere ? 
6770, why theory of compass after all the theories 
in magnetics and why with the earth especially ? 
In specimen slips. It seems necessary to cross 
reference this paper to alternating fields, as it might 
be of interest to one investigating magnetic fields, 
6560 or 6570. 
Witiram HALLoce. 
D. PHYSICS-MECHANICS. 
In compliance with your request I beg to 
submit herewith the following comments on 
the Report of the Royal Society of London 
concerning the project for an International 
Catalogue : 
1. The plan for the proposed work out- 
lined by the report, so far as I can under- 
stand it from a necessarily hasty examina- 
tion, seems to be satisfactory and feasible 
in all essential respects. It appears to 
merit, however, some criticisms as to mat- 
ters of detail, which I proceed to point out 
with some diffidence, since the reasons 
which led the Royal Society’s Committee to 
adopt the present form of their report must 
be partly unknown to me. 
2. My first criticism relates to the 
‘schedules of classification,’ which seem 
to be in some respects retrogressive. 
a. Would it not be better to have the 
‘ Registration letter’ in each case the initial 
letter of the science ? 
b. The prominence given to meteorology 
and the incorporation of mechanics with 
physics seem quite unwarranted as well as 
archaic. The definite parts of meteorology 
and physics are mechanics, and the present 
tendency is towards mechanical interpreta- 
tions of the indefinite parts. It would 
seem to me better to give mechanics a di- 
vision by itself, or to call the proposed di- 
vision Physics and Mechanics, or Natural 
Philosophy. 
Similar, though less strong, objections 
may be urged against the inclusion of 
