May I 9, 1904] 



NATURE 



theory of the microscope, recently read before the Royal 

 Microscopical Society. The object exhibited was a diatom 

 {Pleurosigma atigitlatitm) magnified about 10,000 diameters. 

 — .'\ cylindrical telescope for the rotation of images : Dr. 

 G. J. Burch, F.R.S. This instrument consists of two 

 cylindrical lenses with their axes of curvature parallel, fixed 

 the sum of. their focal lengths apart. Objects seen through 

 it are not magnified, but reversed as by reflection in a 

 mirror. If the telescope is rotated it causes the image to 

 rotate with double the angular velocity. — Large direct vision 

 spectroscope, with ten prisms, automatically adjustable : 

 Mr. P. Heele. — Experiments with non-homocentric pencils : 

 Mr. W. Bennett. — Optical testing bench : Messrs. R. and 

 J. Beck. The bench is so designed that the optical constants 

 of a lens and its various aberrations (chromatic, spherical, 

 astigmatic, &c.) can be rapidly and accurately measured,. 

 and is specially adapted for using the new Hartmann system 

 of testing either by direct vision or by photography. — 

 Examples of photomicrography : Mr. Arthur E. Smith and 

 Mr. Richard Kerr. 



Some new phosphorescent materials : Mr. H. Jackson. 

 Examples were shown of phosphorescent compounds of zinc, 

 strontium, aluminium, calcium, &c., prepared to illustrate 

 varying degrees of response to such exciting influences as 

 violet and ultra-violet light, electric discharge, heat and 

 friction. By varying the constitution of the compounds in 

 the direction of increasing or diminishing their basic or 

 acidic character the length of time during which the 

 phosphorescent glow lasts can be increased or lessened con- 

 siderably, and the property of glowing, when heated, can 

 be made to persist apparently indefinitely. — Photographs 

 illustrative of induced radio-activity of bacteria : Dr. Alan 

 B. Green. Small masses of bacterial growth were exposed 

 to the 13 and 7 rays of 10 mg. of virtually pure radium 

 bromide. In a large number of instances such masses when 

 removed from the influence of the radium and placed between 

 two thin sheets of glass, themselves not radio-active, were 

 capable of so affecting the sensitised film of a photographic 

 plate with which they were brought in contact, that on 

 development in the ordinary way, the plate showed a dark 

 area corresponding to the shape of the bacterial mass. The 

 photo-actinic rays pioceeding from the bacteria which had 

 been exposed to radium were capable of affecting a photo- 

 graphic plate through a double layer of lead foil. 



A method of mechanically reinforcing sounds : Mr. T. C. 

 Porter. .An ordinary " Horrie " Edison-Bell phonograph 

 with the " reproducer " is used as the source of the sounds. 

 In this instrument the roughness of the record makes a rod 

 vibrate, and these vibrations are communicated mechanically 

 to a thin disc of glass or mica, which in turn transmits 

 them to the air on the side of the disc remote from the rod ; 

 the aerial disturbances are then conducted by a tube usually 

 to a trumpet, but in this experiment the reinforcement of 

 the sounds is obtained by the combustion of coal-gas and 

 air. The mixed gases are led over the disc of the " repro- 

 ducer " and conveyed by tubing to two convergent jets and 

 then ignited. A further reinforcement is obtained by placing 

 platinum foil in the flame. — Experiments on lubrication 

 showing cavitation : Mr. S. Skinner. The lubricating fluid 

 in the space, between a bearing and the axle working in 

 it, is subject to conditions in which cavitation, i.e. the form- 

 ation of vacuous spaces in the fluid, can occur. This was 

 shown by a series of experiments, in which the deeply 

 coloured lubricating fluid is contained between glass 

 surfaces, and light is transmitted through the cavities. — 

 ii) Microphone-buzzer (with partially tuned telephone) 

 giving a nearly pure note of 2000 vibrations per second ; 

 -' I apparatus used to investigate the distribution of tempera- 



n^ in the field colls of electric machinery; (3) apparatus 



I rapid electric thermometry : the National Phvsical 

 l..il)oratory. — (i) VIbrograph for recording vibrations photo- 

 ^r.-iphically ; (2) micro-manometer : the Cambridge Scien- 

 tific Instrument Company, Ltd. — Stream gauge for In- 

 rlicating the rate of delivery of air or gas by a pipe : Mr. 

 R. Threlfall, F.R.S. — (i) Stereoscopic views and specimens 

 illustrating the construction of the Simplon Tunnel ; (2) 

 stereoscopic and other views of the Victoria Falls of the 

 River Zambesi : Mr. Francis Fox. 



.Apparatus for the metrical study of stationary electric 

 ives on spiral wires : Prof. J. A. Fleming, F.R.S. The 



[■paratus exhibited consists of a long solenoid of silk- 



covered wire having 5000 turns and a total length of 643 

 metres. This solenoid has parallel to it an adjustable earth 

 wire and a divided scale. The solenoid is connected to one 

 point on an oscillatory electric circuit consisting of a couple 

 of Leydens having a capacity of 000068 mfd. and an 

 adjustable inductance of o to 230 microhenrys and a silent 

 discharger. When oscillations are set up in this circuit 

 by Induction coil discharges and the frequency adjusted, 

 stationary electric waves are set up In the solenoid. The 

 position of the loops and nodes is ascertained by the use 

 of a series of carbonic dioxide vacuum tubes. — Edison's 

 secondary battery (or accumulator) for automobiles : Mr. 

 W. HIbbert and Mr. H. E. Dick. — Electrical instruments of 

 precision : Colonel R. E. Crompton, C.B. — Improved muffle 

 and melting furnaces for use in laboratories or art studios : 

 Mr. H. H. Cunynghame, C.B. The plan on which these 

 furnaces are constructed is to jacket them thickly with non- 

 conducting material, in such a way that heat cannot escape 

 as fast as it is developed, until a high temperature has been 

 attained. — Electric resistance furnaces for laboratory use : 

 Mr. Bertram Blount. 



Specimens illustrating the action that occurs between 

 metals at a temperature many hundreds of degrees below 

 their melting point ; Mr. Sherard Cowper-Coles. — .Apparatus 

 for determining the ignition point of gases : Prof. H. B. 

 Dixon, F.R.S., and Mr. G. W. A. Foster. — Specimens of 

 methvl and other derivatives of sulphur, selenium and 

 tellurium : Dr. A. Scott, F.R.S. 



(i) A new natural order of plants, the Amphlpterygiaceae, 

 Hemsley and Rose; (2) fruits of Melocaiwa bainbusoides, 

 an exalbuminous, viviparous bamboo ; (3) Hydnophytum 

 loiigifolium (Rubiaceae), Fiji Islands; (4) Dischidia 

 rafflesiana (Asclepiadaceae), Malaya; (5) Aspiditim ano- 

 malum, Ceylon : the Director, Royal Botanic Gardens, 

 Kew. — (i) Specimens illustrative of cotton cultivation in 

 British colonies and dependencies ; (2) map showing the 

 " cotton belt " and the British and foreign areas in which 

 cotton is now commercially or experimentally cultivated 

 (from Prof. Dunstan's report on cotton cultivation in the 

 British Empire and Egypt) ; (3) mineral and rock specimens 

 from Ceylon and southern Nigeria; (4) specimens of the 

 seeds of Hcvea brasilicnsis (Para rubber tree) from the 

 Straits Settlements ; Prof. Wyndham R. Dunstan, F.R.S., 

 director of the Imperial Institute. — Microscopic slides Illus- 

 trating nuclear division in cells of malignant growths of 

 man : Prof. J. B. Farmer, F.R.S., Mr. J. E. S. Moore and 

 Mr. C. E. Walker. — Microscopic preparations illustrating 

 the parasitism of the rust fungi or uredineae : Prof. H. 

 Marshall Ward, F.R.S. — Microscopical preparations to show 

 the fertilisation and alternation of generations in the 

 Uredinea; : Mr. V. H. Blackman. — Plants and photographs 

 from the High Andes of Bolivia and Peru : Mr. A. W. Hill. 

 — A series of hvbrid wheats illustrating Mendel's laws : 

 Mr. R. H. Biften. 



The pearl-oyster fisheries of Ceylon : Prof. W. A. Herd- 

 man, F.R.S. — Microscopical preparations and diagrams 

 of the chromatophores of the higher Crustacea : Mr. 

 Frederick Keeble and Mr. F. W. Gamble. The 

 coloration of such Crustacea as Hippolyte varians is 

 due to pigments contained in chromatophores. The 

 chromatophores consist of several compartments, in each 

 of which a single pigment is present. When contracted to 

 the centre of the chromatophore, a pigment plays no part 

 in the coloration of the animal ; when expanded into the 

 superficial network which communicates with the centre, the 

 pigment takes a share in the coloration. — Ticks and tick- 

 transmitted diseases : Dr. G. H. F. Nuttall, F.R.S. The 

 exhibit included specimens of ticks which transmit several 

 diseases ; also specimens of the parasites and figures. — 

 Nematocysts of .-Eolids : Mr. G. H. Grosvenor. — Inter- 

 national North Sea investigations. Results of work during 

 1903, from the Plymouth and Lowestoft laboratories : the 

 ^Iarine Biological .Association. 



.A photographic study of the English skull, 1600-1850 : 

 Prof. Karl Pearson, F.R.S. The photographs of English 

 skulls illustrated normal and abnormal types. There were 

 two series, numbering upwards of 500 altogether, from old 

 plague pits or graveyards in the City of London. Both 

 series were of great interest, and the nearest related group 

 to one of them appears to be long barrow British. — 

 -Apparatus and methods employed for measuring, In the 



NO. 1803, VOL. 70] 



