6o 



NATURE 



[May 2 1, 1903 



measurement of temperatures between 0° and— 253° C. One 

 is graduated directly in degrees on the hydrogen scale, and 

 can be employed for the direct measurement of low tem- 

 peratures to within one degree. The other is intended for 

 more accurate measurements. 



A new coherer, as applied to wireless telegraphy, was 

 shown by Sir Oliver Lodge, F.R.S., and Dr. Alexander 

 Muirhead. A steel wheel rotates so that its edge touches 

 a pool of mercury through a film of oil. (See Froc. 

 Roy. Soc, March.) This is the coherer, and its de- 

 coherence is automatic. A fraction of a volt is used in 

 the detecting circuit, which works a siphon recorder as 

 the receiving instrument. The sending part of a station, 

 including an automatic transmitter and a " buzzer " for 

 carving a steady current into intermittencies, was also 

 shown. 



Incandescent oil burners were exhibited by Mr. T. 

 Matthews. These burners have been designed by the 

 exhibitor primarily for use in the Trinity House Light- 

 house Service. The intensity of the single mantle burner 

 for flashing lights is iioo candles, and the consumption of 

 oil one pint per hour ; the intensity of the triple mantle 

 burner for fixed and occulting lights is 2700 candles, and 

 the consumption of oil three pints per hour, the flashing 

 point of the oil being in each case from 145° to 160° 

 Fahrenheit (close test). 



Experiments on controlling and regulating spark dis- 

 charges, shown by Mr. Alfred Williams, illustrate how the 

 use of a shunt, or of a point and shunt, or of plates of high 

 resistance, so influence the field in a spark gap that the 

 discharges are made more regular and placed more under 

 control for therapeutic and wireless telegraphy purposes. 



The " Elasmometer," a new form of interference 

 apparatus for the determination of the elasticity of solid 

 substances, was exhibited by Mr. A. E. Tutton, F.R.S. 

 The apparatus is designed to measure the amount of bend- 

 ing suffered by a thin plate of the substance investigated, 

 when supported near its ends against a pair of platinum- 

 iridium knife-edges, under a weight applied at its centre. 



Prof. A. G. Greenhill, F.R.S., showed a gyroscopic pen- 

 dulum, for lecture experiment. A bicycle wheel is sus- 

 pended by a prolongation of its axis from a universal joint, 

 formed with a hub and its ball-bearings. The wheel is 

 rotated by a stick inserted in the spokes, and projected to 

 illustrate the variety of gyroscopic motion. 



Dr. W. Ramsden demonstrated by exoeriments and illus- 

 trated by photomicrographs and specimens, the presence 

 and spontaneous formation of solid membranes upon the free 

 surfaces of certain solutions. He also showed that solid 

 membranes are present on certain bubbles. 



Aerial photographs were shown by the Rev. John M. 

 Bacon. Among the pictures was one showing the sea 

 bottom at a depth of ten fathoms photographed from an 

 altitude of 600 feet. 



The physical sciences were also represented by the follow- 

 ing objects and experiments : — A series of photographs and 

 objects relating to Dr. William Gilbert, of Colchester (1544- 

 1603), author of the treatise " De Magnete," Prof. 

 Silvanus P. Thompson, F.R.S. ; a direct vision spectroscope 

 of one kind of glass, and of minimum deviation for any 

 ray in the centre of the field of view, Mr. T. H. Blakesley 

 (see p. 71) ; apparatus for the detection and estimation of 

 minute quantities of arsenic in beer and brewing materials, 

 as recommended by a Departmental Committee of the Board 

 of Inland Revenue, Prof. T. E. Thorpe, C.B., For.Sec.R.S. ; 

 ephelkystika, or tractate curves, and machine for draw- 

 ing them. Col. Hippisley, C.B., R.E. ; (i) gravimetric 

 recording hvgrometer, (2) an electrical dewpoint hygro- 

 meter, Prof. F. T. Trouton, F.R.S. ; Calendar's com- 

 pensated barometer, Mr. N. Eumorfopoulos ; light mirrors, 

 suitable for galvanometers (see p. 72), Mr. W. Watson, 

 F.R.S. ; micrometer for measuring screws, made for the 

 British Association Screw Gauge Committee, the Cam- 

 bridge Scientific Instrument Company ; photographs of dust 

 deposits. Dr. W. J. Russell, F.R.S. ; examples of Lipp- 

 mann's process of photography in colours, Mr. Edwin 

 Edser and Mr. Edgar Senior ; an experiment illustrating 

 the conductivity imparted to a vacuum by hot carbon, Mr. 

 O. W. Richardson ; a high pressure spark-gap used in con- 

 nection with an inductor of the Tesla type, and also in 

 connection with a radiator of Hertzian waves. Rev. F. J. 



NO. 1751. VOL 68] 



Jervis-Smith, F.R.S. ; diagrams illustrating the order and 

 origin of the musical scales, Mr. Joseph Goold. 



An artificial horizon attachment to sextants, exhibited by 

 Commander Campbell Hepworth, C.B., consists essentially 

 of a contact maker, operated by a plummet mounted on a 

 sextant, and connected with a galvanic battery. It is so 

 adjusted as to close the circuit and ring a bell when a slit 

 or line on the horizon glass is in alignment with the eye 

 of the observer and the sensible horizon. Observations for 

 latitude and longitude at sea are rendered impossible when 

 the natural horizon is obscured by fog or mist, although 

 sun, moon, or stars may be shining clearly ; but with the 

 aid of this instrument the observer may obtain the true 

 altitude of a heave'nly body v^fithin five minutes of arc. 



The Solar Physics Observatory, South Kensington, ex- 

 hibited (i) photographic comparison of the arc spectra of 

 various samples of dust ; (2) curves, illustrating the long 

 period solar and meteorological (rainfall) variations of about 

 thirty-five years ; (3) photographs of new curved slit by 

 Hilg'er. This slit is used at the focus of the second objective 

 of the photo-spectro-heliograph, and is intended for the 

 isolation of the K (calcium) line in the solar spectrum, Nos. 

 3 a and h. 



The use of a colour screen in photographing bright stars 

 was illustrated by the Cambridge Observatory. By the use 

 of a yellow spot on a worked glass screen in contact with 

 the sensitive plate, the image of a bright star can be 

 reduced to equality with the images of the comparison 

 stars. It thus becomes possible to apply photography _ to 

 the determination of the parallaxes of bright stars, which 

 have been dealt with hitherto almost entirely by the helio- 

 meter. 



The chromospheric spectrum near the South Pole of the 

 Sun was shown by Mr. J. Evershed. Nebular spectra of 

 Nova Persei from May 3, 1901, to January 14, 1902, with 

 previous spectra 'for comparison, were illustrated by Mr. 

 Frank McClean, F.R.S. Other exhibits were :— (i) coUi- 

 mating gun sight for day and night ; (2) optical sight for 

 guns and rifles ; (3) spherometer of great delicacy, by Dr. 

 A. A. Common, F.R.S. 



Methods of disintegrating cells and microorganisms, and 

 of obtaining their intracellular constituents, were shown 

 by Dr. A. Macfadyen and Mr. S. Rowland. In the first 

 method the cells are disintegrated by the violent impact of 

 sand particles in the apparatus exhibited. In the second 

 method the use of extraneous disintegrating material is 

 dispensed with, the cells or organisms being disintegrated 

 when in a frozen condition. In the apparatus exhibited the 

 necessary cold and brittleness are secured by the use of 

 liquid air. 



Dr. Leonard Rogers exhibited five specimens of Hydro- 

 phidiE (poisonous sea snakes). These snakes swarm round 

 the coasts of India and in other tropical seas, and cause 

 some loss of life among fishermen. Their poison has 

 lecently been found to be more powerful than that of any 

 other snakes. 



Miss E. R. Saunders illustrated interesting cases of struc- 

 tural atavism resulting from cross-breeding. Experiments 

 (Report Evolution Committee, 1902) with stocks suggested 

 that when glabrous plants of dissimilar colours are crossed 

 together, the offspring might be hoary. Actual trials have 

 proved this to be true. When glabrous cream or white 

 are crossed with each other, or with glabrous plants of other 

 colours, the offspring are all hoary ; but when colours other 

 than white or cream are crossed together, the offspring are 

 all glabrous. 



Fossils in Cambrian quartzite were shown by Prof. J. 

 Norman Collie, F.R.S. These fossils were found on the 

 surface of a glacier in Desolation Valley (near Laggan 

 Railwav Station), Canadian Rocky Mountains. 



Dr. Henry Woodward, F.R.S., exhibited two photographs 

 of Tetrabelodon (Mastodon) angustidens, Cuvier, from the 

 Miocene of Sansan, France, taken from the skeleton in the 

 Museum of Natural History, Paris. This primitive form of 

 Mastodon still retains two pairs of functional incisor teeth 

 (tusks), one pair in the upper and one pair in the lower jaw, 

 the upper ones being directed downwards. In modern 

 elephants only one pair (the upper) incisors are present, and 

 these are usually curved upwards. (See Dr. C. W. Andrews's 

 paper, Proc. Roy. Soc, No. 474.) 



The Royal Geographical Society had on view (i) hypso- 



