622 
NATURE 
[APRIL 25, 1907 
measurement with a foot-rule and a protractor graduated 
in radians. A geometrical analysis was given, confirming 
the accuracy of the experimental results, and affording an 
independent proof of the exponential theorem. A second 
spiral was drawn with an angle tan-'M, thus giving 
common logs. in terms of the radian, and it was shown 
that, by using a suitably graduated protractor or modulus, 
one system transformed into the other. A Boucher’s circle 
and a slide-rule were also derived practically from the 
spiral. The differentials dlog.r/dry and dlog,,r/dr were 
shown graphically, as well as the properties of the evolute 
and involute.—Logarithmic lazy-tongs and. lattice-works : 
T. H. Blakesley. If two straight rods, AB, CD are 
jointed at E, and so related that the extremities ACBD 
lie in the circumference of a circle, they will fulfil this 
condition when the angle between is changed. Suppose 
that AE is taken as unity, and that ED=n, EC=m, 
m and n being quite independent. Then EB=mn as a 
consequence. If another pair of rods, DF, BG, similar 
to the first pair but bearing the ratio n:1 to it, be jointed 
at D and B to the first pair, and to the extremities FG 
of this pair a third pair be again jointed, and a fourth 
to this and so on, the ratio of each pair to the preceding 
one being n:1, the resulting linkage is called by the 
author a logarithmic lazy-tongs. A lazy-tongs constructed 
as above is said to be in the nm direction. Any of the 
four sides AC, CB, BD, AD might be chosen as that to 
which the next pair of rods is to be attached, care being 
taken to make the ratio correspond to the direction 
chosen. If CB is chosen the ratio must be m:1, and a 
lazy-tongs in the direction m will result, the angular shift 
at each step being EAD—EDA. Suppose pairs added in 
the m direction to both CB and BF; then these two pairs 
will have, in addition to B, another common point, viz. 
that which is homologous to B in the m direction. In 
fact, the same pair is arrived at whether by moving once 
in the m direction and then once in the m direction, or 
vice versd. It is clear that a joint may be added at the 
common point, and that the rule is a general one, hence 
all plane space may be occupied by such a linkage, which 
is called a logarithmic lattice-work. Such a lattice-work 
moves so that the angles at E, and points homologous, 
will remain equal. 
Geological Society, March 27.—Sir Archibald Geikie, 
Sec.R.S., president, in the chair.—The southern origin 
attributed to the northern zone in the Savoy and Swiss 
Alps: Prof. T. G. Bonney. Prof. Lugeon, with some 
other eminent Continental geologists, explains certain 
peculiar flat folds, the higher of which sometimes project 
considerably beyond the lower, in the more northern .sedi- 
mentary zone of the Swiss and Savoy Alps, by supposing 
that to no small extent the strata have been thrust for- 
ward -from an original position south of the watershed 
of the Pennine-Lepontine Alps, overriding, as _ they 
advanced, their crest and that of the Oberland (neither 
having then attained its present altitude). This pressure 
was produced by the greater thickness of deposits of mid- 
Tertiary age, speaking in general terms. Prof. Sollas, in 
concluding a very interesting and suggestive paper on 
some experiments with cobbler’s wax, published in the 
last volume of the Quarterly Journal of the society, p. 716, 
suggests that the results are favourable to the views of 
the Lausanne professor. The author takes exception to 
some of the cases, especially two to the east of the Simplon 
Pass, which are adduced by Prof. Lugeon in support of 
his hypothesis. It is maintained that the hypothesis re- 
ceives no real support from Prof. Sollas’s experiments, and 
involves mechanical difficulties which are practically in- 
superable.—The coral-rocks of Barbados: Prof. J. B. 
Harrison. The results of the author’s extended, and in 
many places detailed, re-examination of the coral-rocks in 
the southern half of Barbados give no support to Dr. 
J. W. Spencer’s theory of the existence of strata of the 
“Antigua formation’? in that island. It is now shown 
that a certain knoll, whence Dr. Spencer collected corals 
which in his estimation proved that it and other parts of 
the coral-rocks were of Oligocene age, is in part made 
up of corals which, as stated by Prof. J. W. Gregory, 
“certainly show no evidence of any age greater than the 
the widespread formation, described in Dr. Spencer’s paper 
as extending from Mount Misery to near Ragged Point, a 
distance of about eleven miles, and dipping -south-eastward 
at from 12° to 20°. 
Society of Chemical Industry, April 8.—Mr. R. J. 
Friswell in the chair.—Observations on cotton and nitrated 
cotton: H. de Mosenthal. This paper deals with the 
appearance of celluloses and nitrocelluloses in polarised 
light, their refractive indices and optical activity, as well 
as densities. Fourteen samples of nitrated cottons of 
different degrees of nitration, different solubility and 
viscosity, three samples of nitrated wood cellulose, and 
two each of nitrated ramie and flax, were examined. The 
appearance in polarised light was found to vary with the 
degree of magnification and the light used, fibres appear- 
ing differently when dry and when moistened. Various 
moistening liquids gave different results. The colours 
shown in polarised light under the same conditions seemed 
to be chiefly dependent on the material nitrated and the 
method of nitration, and they cannot be regarded as a 
function of the degree of nitration. The densities of 
celluloses and of nitrocelluloses examined were found to 
be higher than those recorded in text-books. The densities 
of the nitrated material in solution were also determined, 
and found to be higher than in the solid state. Observ- 
ations of the refractive index of nitrated cotton in solution 
gave results which were not concordant, and therefore 
determinations were made on transparent films of nitrated 
cotton, ramie, and flax. The refractive index of cellulose 
was found by examining denitrated films and then by 
placing fibres in a liquid of like refraction. Atomic re- 
fractions were applied to some of the proposed formule 
for cellulose, and showed that the cellulose molecule has 
no double bonds. 
Entomological Society, April 10.—Mr. C. O. Water- 
house, president, in the chair.—Wet- and dry-season forms 
of Pierine: Dr. F. A. Dixey. Specimens were shown 
of Pierinz belonging to the genera Teracolus and Huphina. 
The exhibit was intended to illustrate the fact that in 
species of which the wet-season phases were very distinct 
from each other, the corresponding dry-season phases 
often could only be discriminated with difficulty—Forms 
of Osphya and concurrent species: J. Edwards. Five 
forms of Osphya were shown, together with certain other 
species occurring at the same time and place, and, having 
regard to gait and appearance, resembling them more or 
less closely. It was not suggested that these resemblances 
are protective. Attention was also directed to an important 
function of the hind-legs of the male, namely, to secure 
him in position at the time of pairing.—Antennae-joints in 
Trachiscelis: H. J. Carter. A microscopic slide prepared 
to demonstrate that the antenna of the genus Trachiscelis 
have eleven joints, and not ten as hitherto described.— 
Odonata collected by Lieut.-Colonel C. G. Nurse, chiefly 
in North-Western India: K. J. Morton.—The life-history 
of Cydimon (Urania) leilus: L. Guppy, jun. This paper 
was followed by a discussion on the migration habits and 
classification of the species. 
EDINBURGH. 
Royal Society, February 18.—Dr. Robert Munro, vice- 
president, in the chair.—The coat colour in horses: Prof. 
J. C. Ewart. (1) The remote common ancestor of the 
Equidze was probably of a reddish-brown (foxy-red) colour. 
(2) Horses prior to domestication probably varied in colour 
and consisted of (a) species adapted for a forest life, 
having dark yellow-dun coat, a broad dorsal band, and 
stripes more or less distinct on the face, neck, trunk, and 
legs; (b) species like Prejvalsky’s horse, adapted for a 
steppe life, having a brown yellow or reddish-brown coat, 
a narrow dorsal band, but only at the most vestiges of 
shoulder and leg stripes; and (c) species adapted for a life 
on the plains, having a light yellow-dun coat and, in 
addition to a narrow dorsal band, only faint vestiges of 
stripes on theglegs. (3) Yellow duns belonging to different 
varieties may, when crossed, give rise to bay and chestnut 
as well as yellow-dun offspring. (4) Bays obtained by 
crossing yellow-duns may, when crossed with pure yellow- 
duns, yieid black and chestnut as well as bay offspring. 
(5) Chestnuts derived from crossing yellow-duns may, when 
Pleistocene.’? The author has failed to find any signs of j crossed with pure yellow-duns, yield white and bay as 
NO. 1956, VOL. 75 | 
