Fune 9, 1870] 
NATURE 
115 
muscles of the fore arm act upon the finger tendons, in a direc- 
tion from the muscles towards the tendons, which latter undergo 
friction at the wrist and other joints of the hand, the force 
being applied by the muscles to the tendon above the wrist, and 
the resistance being applied at the extremities of the tendons 
below the wrist by the object grasped by the hand. From the 
principle of “ Least Action in Nature” we are entitled to assume 
the strength of each portion of a tendon to be proportional to 
the force it is required to transmit ; and since, in a proper hand, 
these forces are continually diminished by friction, as we proceed 
from the muscle to the fingers, we should expect the strength of 
the tendon above the wrist to be greater than the united strengths 
of all the finger-tendons. Conversely, in a proper foot, the 
force is applied by the ground to the extremities of the tendons 
of the toes, and transmitted to the flexor muscles of the leg, by 
means of the tendons of the inner ankle, which undergo friction 
in passing round that and the other joints of the foot. In this 
case, therefore, we should expect the united strengths of the 
flexor tendons of the toes to exceed the strength of the flexor 
tendons above the heel. In the case of the hand, friction acts 
against the muscles ; in the case of the foot, friction aids the 
muscles. I have measured the relative strengths of the deep 
flexor tendons of the hand above and below the wrist in several 
animals, and also the relative strengths of the long flexor tendons 
of the foot above and below the ankle, in the following man- 
ner :—I weighed certain lengths of the tendons above the wrist 
and ankle, and compared these weights with the weights of 
equal lengths of the flexor tendons of the fingers or toes, assum- 
ing that the weights of equal lengths are proportional to 
their cross sections, and these again proportional to the 
strengths of the tendons at the place of section. The difference 
between the weights above and below the joint represents the 
sum of all the frictions experienced by the tendons between the 
two points of section. Tables are given showing the results of 
measurements, ¢.g., in the case of the Pyrenean Mastiff the 
amount of friction is 65°4 per cent., while in the Boomer Kan- 
garoo it is #/. The foregoing animals all realise the typical 
idea of a true foot, with a variable amount of friction at the 
ankle-joint ; this friction disappearing altogether in the Boomer 
Kangaroo, whose method of progression realises absolute me- 
chanical perfection, as no force whatever is consumed by the 
friction of the flexor tendons at the heel. The only animals 
whose feet deviated from the typical foot were three, viz., the 
Alligator, common Porcupine, and Phalanger. In these animals 
the foot has the mechanical action of a hand, or grasping organ ; 
and the flexor tendons above the ankle exceeded those below the 
ankle by the following amounts :—Alligator, 11°5 per cent. ; 
common Porcupine, 20°0 ; Phalanger, 29°2. In the case of the 
flexor tendons of the hand results were obtained varying from 
71° in the case of the Common Porcupine, to wz/ in the case of 
the Goat. It will be observed thatjthe fore foot of the goat, re- 
garded simply as an organ of locomotion, attains a perfection 
comparable with that of the hind foot of the kangaroo, no force 
being lost by friction at the wrist-joint. The only animal in 
which I found a departure from the typical hand was the Llama, 
in which the flexor tendons.of the fingers exceed the flexor ten- 
don above the wrist by 14°4 per cent. The bearing of the fore- 
going results on the habits of locomotion of the several animals 
will suggest themselves at once to naturalists who have carefully 
studied those habits. I shall merely add that the subject admits 
of being carried into the details of the separate or combined 
actions of the several fingers and toes, and that the habits of 
various kinds of monkeys in the use of certain combinations of 
fingers or toes may be explained satisfactorily by the minute 
study of the arrangement and several strengths of the various 
flexor tendons distributed to the fingers or toes. 
PARIs 
Academy of Sciences, May 23.—M. Jordan communi- 
cated a theorem on doubly periodical functions.—A note by 
M. L. Cailletet on the compressibility of gas at high pressures, 
was communicated by M. H. Sainte-Claire Deville.—M. 
Chapelas presented a note on the aurora borealis of the 20th 
May, which was observed to move from west to east, and was 
followed by great atmospheric disturbances coming from the 
south-west.—M. E. Lagout described a cheap equatorial sun- 
dial which he has invented for the purpose of regulating time- 
pieces. It costs from 8 to 12 francs.—M. A. Trecul presented 
a note on the hailstones which fell at Paris during the storm of 
the 2gnd May. These were pear-shaped, and very large, some 
measuring more than three-quarters of an inch in length. 
One of them showed at its larger end the form of an obtuse- 
angled rhombus.—A note on the clouds, fogs, and rains with 
sand, observed in Italy in 1869, by M. Zantedeschi, was read.— 
Several chemical papers were communicated, namely :—A 
memoir on the action of water upon iron, and of hydrogen 
upon oxide of iron, by M. H. Sainte-Claire Deville. A report by 
M. Cheyreul on a memoir by M. Vétillart on the vegetable 
fibres employed in manufactures, describing the distinctive 
characters of the principal textile materials as evinced by 
microscopic observation and by treatment with iodine and sul- 
phuric acid. A note by M. Schiitzenberger on the compounds 
of protochloride of platinum with oxide of carbon ; one by M. 
M. Prudhomme on the action of acetylene upon acetohypo- 
chlorous anhydride (acetate of chlorine) ; and one by the same 
author, on the action of sulphuric anhydride upon protochloride 
and sesquichloride of carbon, all communicated by M. H. Sainte- 
Claire Deville.—Observations on the constitution of the flame of 
the fish-tail gas-burner, by M. A. Baudrimont. The author 
found that the obscure part of the flame possesses heat sufficient 
to fuse a platinum wire.—A note by M. A. Vezian, on the 
system of mineral veins of the Hundsriick, was read ; and an 
extract from a letter by M. de Botella, noticing two recent 
cases of elevation of land in Spain. Upon the latter M. Elie 
de Beaumont made some remarks. —M. Cl. Bernard presented a 
contribution to the knowledge of the minute structure of the 
mammary gland, by MM. G. Giannuzzi and E. Falaschi. M. 
d’Abbadie suggested the desirableness of a decimal division of 
the circle and of time; and General Morin presented a note on 
some earthenware stoves, manufactured by Miiller and Co., of 
Ivry, which, as he stated, utilise no less than 93 per cent. of the 
heat developed by the coke consumed in them. Several other 
papers and communications were read of which the titles only 
are given. 
May 30.—A paper by M. E. Combescene on some differen- 
tial formulze was presented by M. Hermite; and a note on a 
formula of analysis, by M. F. Lucas, was communicated by 
M. Liouville. General Morin communicated a memoir by 
MM. C.. Martins and G. Chancel on the physical pheno- 
mena which accompany the rupture of hollow projectiles of 
various calibres by the congelation of water contained in them. 
The numbers obtained by the authors are about one half 
those obtained by General Morin from the formule given by 
him in his lectures on practical mechanics. General Morin, 
M. Dumas, and M. Elie de Beaumont made some remarks 
upon this communication. —M. Jamin presented a note by 
MM. A. Cornu and E. Mercadier, on melodic and harmonic 
intervals, in reply to a paper by M. Gueéroult, read on May 
g.—M. Jamin also communicated two notes by M. Tréve on 
electriccurrents. In oneof these the author cited some further 
observations in support of his assertion that two currents cannot 
circulate in opposite directions in the same wire or in the same 
‘Geissler’s tube ; in the second he indicated a method of explain- 
ing the course of the currents in telegraphy when terrestrial 
communications are employed without a return wire. He main- 
tained that the soil is to be regarded as a common reservoir rather 
than as a conductor.—A note by M. J. Mario on the phenomena 
of electrostatic induction was read. From his experiments he 
proposed a theory of terrestrial currents, according to which the 
sun would be a source of positive electricity acting by induction 
upon the earth.—A note by M. Neyreneuf, on the theory of 
electrical condensers, was also read.—The following papers on 
chemical subjects were read :—A note. by M. Cloez, claiming 
priority in the discovery of the cyanic and cyanuric ethers, 
presented by M. Cahours.—A note by MM, Gal and Gay- 
Lussac, also presented by M. Cahours, on some compounds 
homologous with tartaric and malic acids. These compounds 
were adipomalic, adipotartaric, suberomalic, and suberotartaric 
acids ; they are obtained by the action of bromine upon adipic 
andsubericacids.—A note on the action of hydrochloric acid upon 
osseine, including researches upon determination of the quantity 
of osseine in fossil bones, by M. Scheurer Kestner, communicated 
by M. Balard. The author stated that the solubility of a portion of 
the osseine in bones is independent of the action of hydrochloric 
acid, which may be reduced toalmost nothing by sufficient dilution. 
He replied to some remarks of M. Elie de Beaumont on his former 
paper on this subject.—A note, by M. Sacc, on the preparation 
of pyrotartaric acid. The process proposed by the author cori- 
sists in disolving anhydrous tartaric acid in commercial acetic 
acid, and heating the mixture in a retort until it becomes 
