NATURE 



[December 26, 1907 



Hill, Oxon, and at Crinan, on the west coast of Scot- 

 land; -Mr. J. E. Petavel, at Manchester University; Cap- 

 tain C. H. Ley, R.E., at Sellack, Herefordshire; and Mr. 

 C. J. P. Cave, at Ditcham Park, Petersfield. Fourteen 

 of the registering instruments have been found. Prof. 

 VV. E. Thrift also sent up a number of pilot balloons from 

 Dublin. Nearly all the balloons drifted to the eastward, 

 but several which reached a fair height fell within twenty 

 miles of their starting point. The heights ranged up to 

 more than lai miles, the average being about yj miles. 

 The records showed that above 7J miles the temperature 

 remained almost unaltered with change of height. — Dis- 

 cussion of the meteorological observations at the British 

 kite stations, session 1906-7 : Miss M. White, T. V. 

 Pring, and J. E. Petavel. The authors found that the 

 temperature gradient varies with the direction and the 

 velocity of the wind, and also with the amount of clouds, 

 being greatest for a north-west wind, and on clear and 

 fine days. It appears that the direction of the wind alters 

 at high levels, rotating in a clockwise direction ; thus a 

 south wind tends to become more westerly. 



December 18. — Dr. H. R. Mill, president, in 

 the chair. — The possibility of a topography of 

 the air, based on balloon observations with special 

 theodolites : Capt. C. H. Ley. The author gave 

 the results of his own observations in Herefordshire 

 in connection with the international balloon ascents which 

 were carried out during the past summer. His method of 

 observing is based on the direct estimation of the range 

 of the balloon from its apparent diameter as measured 

 by cross threads in a telescope ; the range being thus 

 determined, an altitude and azimuth are read, and the 

 position if the balloon fixed and plotted on a map. The 

 author, in conclusion, states that the varying topography 

 of the earth's surface produces disturbances in tlie atmo- 

 sphere with effects which are transmitted throughout the 

 lower and middle strata ; and that the general effect on 

 a current is to increase its velocity over a hill and decrease it 

 over a valley, and this is especially the case with the vertical 

 velocity. The origin of the phenomena is to be sought in 

 the mechanical effect of obstruction of the lowest stratum, 

 but there are probably various ensuing complications which 

 may accentuate the result. The measurement of these 

 effects can be carried out by a topography of the air 

 made in any locality. — Indications of approaching frost : 

 R. Strachan. For the purpose of making forecasts, the 

 dry and wet bulb thermometers should be noted at or 

 after sunset, or at g p.m., and the amount of cloud at 

 the time, and during the forepart of the night if con- 

 venient. The dew point can be found by reference to 

 hygrometrical tables. When the dew point is at or below 

 32° frost is in evidence, but may be evanescent, due to a 

 rise of temperature, with change of wind, rain, or over- 

 cast sky. Even when it is above 32°, if the sky is clear 

 it is possible that the temperature on the ground will 

 become low enough for frost to form. Thus the evening 

 observations should lead to a good idea of what may 

 happen during the night. 



Royal Microscopical Society, November 20. — Lord Ave- 

 bury, president, in the chair. — Exhibits. — Conrad Beck : 

 Two specimens under microscopes of photographic plates pre- 

 pared by the Lumi^re starch-grain process for colour photo- 

 graphy. One specimen had been exposed and the other 

 had not. The starch grains, which were about i/2000-inch 

 in diameter, were stained red, violet, and green. If the 

 object-glass of the microscope showing the unexposed plate 

 be racked out of focus, so that the colours be blended, .a 

 very close approximation to whjte light is obtained. If 

 the objective be only partially out of focus, patches and 

 channels of colour are visible, due to the fact that the 

 coloured grains are not sufficiently intermingled. These 

 patches are what were seen under the microscope exhibited ; 

 to see the individual grains a mucli higher power than 

 the J-inch used would be required. — C. L. Curties : Two 

 inexpensive microscopes. The first, termed the " nature- 

 study " microscope, was mounted on a heavy square foot. 

 It was non-inclinable, and for observing large objects the 

 stage and mirror could be removed and the specimen placed 

 on the fiat base. The other instrument, named the " meat 



examiner's " microscope, is of similar design, but the stage 

 has grooves on its upper surface, from front to back, of a 

 pitch equal to the field of view of a i-inch objective ; a 

 compressor having points projecting from its under side to 

 fit into the grooves is supplied ; by sliding the compressor 

 in one groove and then in the next, until the whole length 

 has been traversed, the entire specimen can be examined 

 without going over the ground two or three times. — J. T. 

 Piss ■ Photomicrographic lantern-slides from nature, show- 

 ing the various stages in the development of the fern spore 

 from its germination to the mature frond with its fructifi- 

 cation. — E. Moffat : A new form of filler for agar and 

 other media. — Papers. — The Frangois Watkins microscope : 

 E. M. Nelson. — Mercury globules as test objects for the 

 microscope: J. W. Gordon. — Light filters for photomicro- 

 graphy : E. Moffat. — Demonstration of the use of colour 

 photography in metallurgy : E. F. Law. A number of 

 photomicrographic lantern-slides were exhibited showing the 

 brilliant colours produced on the polished surfaces of alloys 

 by the varying degrees of oxidation caused by the heat- 

 tinting process. 



Physical Society, November 22. — Prof. j. Perry, 

 F.R.S., president, in the chair. — Specimens of singing 

 sand from New England : S. Skinner. The specimens 

 shown were from two sea-beaches in New England, one 

 at Manchester, Mass., and the other near Small Point, 

 Maine. The beaches are alike in character in being 

 surrounded by hard rock walls and in not having streams 

 which might bring silt flowing through them. The sands 

 are consequently very clean and free from small particles, 

 and this especially so after each tidal washing. The sand 

 consists chiefly of angular clear quartz fragments. Mr. 

 Skinner has been able to verify most of the facts observed 

 by Mr. Carus Wilson (N.4TURE, 1891), viz. : — (i) the sounds 

 are best obtained by plunging a hard plunger into a glazed 

 cup containing the sand ; (2) after a time the production 

 of the sounds becomes difficult ; (3) the sounding may be 

 restored by washing, which presumably removes fine 

 powder formed by attrition between the particles ; (4) it is 

 necessary that the displacement of the sand by the plunger 

 should occur easily. If there is resistance due to the shape 

 of the vessel, or due to clogging by dust, the sounding is 

 stopped. The theory put forward in " Sound " by Profs. 

 Poynting and Thomson seems a reasonable explanation. — A 

 micromanonieter : L. Bairstow. The instrument exhibited 

 was one of two which are in regular use at the National 

 Physical Laboratory for measurements of pressures due to 

 air currents. When the pressures on the two sides of the 

 g.auge are balanced, the whole of the liquids employed 

 are in their zero positions, and errors due to capillarity and 

 viscosity are avoided. The gauge exhibited has a sensitive- 

 ness of I / 10, 000th of an inch of water and a range of 

 three-fourths of an inch of water. The gauge is slightly 

 sensitive to temperature due to the expansion of the castor- 

 oil used, but the changes are small and easily allowed for 

 bv taking time readings of the zero. The gauge is not 

 suitable for rapidly varying pressures, as considerable dis- 

 tortion of the oil surface leads to an irregularly displaced 

 zero. — A diabolo experiment : C. V. Boys. The diabolo 

 spool exhibited has the peculiar merit that no one can 

 spin it. It is based upon the following principle. Either 

 the ordin.ary spool of commerce, which has its moment of 

 inertia about its axis of rotational symmetry a minimum, 

 or a spool not generally made which has the corresponding 

 moment of inertia a maximum, has stable rotation about 

 this axis or about a transverse axis, i.e. if it is temporarily 

 rotating about an axis inclined to one or other, it will 

 tend to shift its momentary axis of rotation and gradually 

 settle down so as to spin about one or other. If, however, 

 the spool is so proportioned that the moment of inertia is 

 identical about any axis, it has no tendency to spin stably 

 about any particular axis, and the axis of rotation wanders 

 about so rapidly that it cannot be spun. A heavy conical 

 sheet projecting equally on either side of the _vertex, the 

 semi-vertical angle of which is equal to tan-'*/2, has this 

 propertv, but such an ideal construction is impracticable. 

 .Ml added matter beyond the sheet in the direction of the 

 axis makes the momental ellipsoid more prolate, while 

 anv outside the sheet makes it more oblate. Treating, 



NO. IQ9I, VOL. 77] 



