232 



NATURE 



[January 3, 1895 



known difficulty of identifying the former level is overcome by 

 Sgr. Goglielmo in a manner described in the current Atti del 

 Linen. He grinds the edges of a beaker, and mounts inside it 

 a pointer of glass or platinum so that iis line point lies just in 

 the plane of the edge. This is accomplished while the mount- 

 ing cement is still soft, by inverting the beaker on a plane 

 surface, and thus pressing the point into its place. A burette 

 with an india-rubber tube enables the observer to add or 

 withdraw a known volume of water. In order to measure the 

 volume of a solid, the plane horizontal edge of the beaker is 

 lightly spread with grease or paraffin, and the beaker is filled 

 up until the unevenness in the liquid surface produced by the 

 pointer has just disappeared. A volume of water larger than 

 the solid is then withdrawn, and the latter is immersed. The 

 liquid is then brought up to the point again, and the difference 

 of level in the burette is the volume required. The rttlection of 

 the bar of a window or other straight line in the liquid is 

 useful for discovering any deformation of the surface. If the 

 pointer should not be easily wetted, a few drops of soap 

 solution are recommended, or the substitution of petroleum for 

 water. 



The comparison of condensers of small capacity and the 

 measurement of the specific inductive capacity of liquids is of 

 considerable importance. An interesting paper on this subject 

 was read by Prof. Nernst, of Gultingen, before the German 

 Electro-Chemical Society (see also /.eilschrift J'nr Physikilische 

 Ciicmie, vol. xiv. p. 622), in which he describes a method for 

 measuring the specific inductive capacity and specific resistance 

 of liquids. The author uses a modification of De Santy's method, 

 in which a telephone is used in place of a galvanometer, alter- 

 nating currents supplied by a small induction coil being used. 

 The resistances employed in the bridge must necessarily be 

 non-inductive, and also, since the capacities to be compared 

 are very small, of practically evanescent electrostatic capacity. 

 Mence the author uses liquid resistances contained in fine cap- 

 illary tubes, the electrode at one end consisting of a fine plati- 

 num wire, which can be moved along the bore of the tube by 

 means of a micrometer screw, and thus the resistance of the 

 liquid column be varied at pleasure. An air condenser is used 

 as a standard with which to compare the condenser containing 

 the liquid under observation, and when this liquid is not a 

 perfect insulator the telephone cannot be brought to com- 

 plete silence by altering the resistances. To overcome this 

 difficulty the author places a high resistance shunt on the air 

 condenser, which is adjusted so that complete silence is 

 obtained. 



A SYSTKM of two pendulums joined by an elastic thread has 

 been studied by M. I.ucien de la Rive, and the results of his 

 experiments are given in the yonrnal de Physique. The 

 masses and the lengths of the twj pendulums were ^equal, and 

 the elastic threads consisted of pure unvulcanised caoutchouc, 

 long enough to make the amount of stretching small in compari- 

 son with their length. It was found that there was a periodical 

 transmission of energy from one pendulum to another. On 

 starting one pendulum, and arranging the thread so that it 

 always remained stretched, the other pendulum started swinging 

 with increasing amplitude, until the first was for an instant 

 reduced to rest. .Vfter that the second pendulum was gradually 

 reduced to its minimum, which did not, however, attain zero, 

 while the other reached its maximum. This transmission of 

 energy exhibited a fixed period, which could be derived from 

 the ordinary period of each pendulum by multiplying with 

 a number proportional to the length, and inversely pro- 

 portional to the sectional area of the thread. In the end, 

 the pendulums tend to oicillatc like a rigid system, with a 

 constant tension of thread, .\fler ten or twelve oscillations, 



NO. 1314, VOL. 51] 



the alternation of periods is hardly perceptible. When one 

 pendulum only was attached to a fixed point by an elastic thread, 

 the decrement was observed in order to determine the internal 

 friction of the thread. This internal friction gives rise to an 

 elevation of temperature which has been exhibited by Warburg, 

 who placed india-rubber tubes round glass tubes containing 

 sounding columns of air, and observed the rise of temperature 

 in the caoutchouc. It shows an analogy to that in wires due to 

 electric currents. 



Ox October 27, as we have recorded in a previous number 

 (p. 18), a disastrous earthquake occurred in .\rgentina. The exact 

 time is as yet unknown, and it is therefore uncertain whether 

 any connection exists between this earthquake and a remarkable 

 series of pulsations that were registered on the same day in 

 several European observatories. At Rome, a very slight and 

 comparatively rapid movement of the great seismometrograph 

 (length, l6m., mass, 200 kg.) commenced at gh. 7m. 35<:., p.m. 

 (Greenwich mean time). This lasted until gh. 40m., when the 

 slow pulsations began to be visible. The first maximum occurred 

 at 9h. 49m. 50s., and the principal one at 9h. 55m. 40s. The 

 amplitude then rapidly diminished, with occasional maxima, 

 the disturbance lasting until about It p.m. Pulsations were 

 also recorded at about the same time at the geodynamic observa- 

 tories of Siena, Ischia, Pavia, and Rocca di Papa. The period 

 of the complete oscillations at the time of their maximum ampli- 

 tude was found to be 167 seconds at Rome, and about 18 

 seconds at Siena and Rocca di Papa. In the south of Russia, 

 at Charkow and Nicolaiew, horizontal pendulums were strongly 

 disturbed. K\. the former pl.ice, the movement began at 

 gh. 8m. 363., p.m., and, for more than an hour, was so great 

 that all traces of the i>hotographic curve disappeared. The 

 large oscillations lasted until lib. 9m. 48s., and the small ones 

 until oh. icm. 54s. a.m., of the following day. At Nicolaiew, 

 the disturbance was first perceptible at 9h. 12m. 6s., p.m., and 

 the curve disappeared almost completely between 9h. 24m. 6s. 

 and loh. 2m. 6s., the pendulum continuing in oscillation until 

 oh. 37m. 65., a.m., of the next day. The magnctographs at 

 Utrecht and Wilhelmshavcn also showed traces of the pulsations, 

 at the former place beginning at gh. 45 m. 28s., and reaching a 

 maximum at 9h. 56m. 2Ss., at the latter beginning at 

 gh. 5Sm. 25s. and ending at loh. iim. 55s. No disturbances 

 are perceptible on the magnetograms at Lisbon, Perpignan, 

 Paris, Kew, Greenwich, Stonyhurst, Vienna, and St. 

 Petersburg {Boll. Meteor., Suppl. 112). 



The last issue oi Studies from the Yale Psychological Labora- 

 tory contains an interesting record of Dr. Gilbert's researches 

 UQ the mental and physical development of schoolchildren 

 between the ages of six and sevenlpen years. On the physical 

 side, statistics are given of increase in (a) weight, (//) height, and 

 (<) lung-capacity. On the psychological side, there are observa- 

 tions on the development of the power of perception and dis- 

 crimination as exercised upon (a) weights poised in the hand, 

 (l>) colour-dilTerences in a scries of shades of red, and (c) time- 

 intervals. To these are added observ.itions on the "force of 

 suggestion," in which, by means of a seiies of lo.tded blocks (l) 

 of different sizes but the same weight, and (2) of different sizes 

 and different weights (the two being nowise correlated), it is 

 shown that visual perception of size very markedly affects 

 weight-discriminations. Reaction time, with and without dis- 

 crimination and choice, was tested ; and observations were made 

 on the influence of fatigue on " voluntary motor ability " as 

 measured by the rapidity of tapping with the key of a specially 

 devised piece of apparatus. In all cases the results, both for 

 boys and girls, are summarised in curves on the graphic method. 

 One of the interesting features to be noticed in these curves is the 

 influence of puberty on mental development, there being a 



