712 



NATURE 



[February 27, 191; 



species : Chenopodiaceas 94, Papilionacese 85, Cruci- 

 ferae 51, Gramine£e 44, Boraginaceae 42. Interest- 

 ing comparisons are drawn between the Transcaspian 

 llora and the floras of various other regions, desert 

 ;md otherwise, with reference to the proportional re- 

 presentation of the families and also of the biological 

 lypes. The memoir concludes with detailed notes 

 on the structure and biological adaptations of various 

 Transcaspian species investigated by the author. 



F. C. 



THE "AEROSCOPE" KINEMATOGRAPH 

 HAND CAMERA. 



AN interesting demonstration of the greatly extended 

 -'y*- adaptability of kinematographic apparatus was 

 given by Mr. Kasimir Proszynski at a meeting of 

 tlie Royal Photographic Society on Tuesday, February 

 18. In introducing the "Aeroscope" hand camera, 

 the lecturer made some general remarks dealing with 

 the problem of flicker, the presence of which, more 

 or less pronounced, has been of considerable trouble 

 to producers of moving pictures. He stated that up 

 to the present time it had been generally understood 

 that the suppression of flicker was in some manner 

 due to the phenomenon of persistence of vision, which, 

 according to the experiments of Helmholtz and other 

 investigators, continues about one-seventh of a second 

 after the light impression has ceased. 



.\'Ir. Proszynski considers this idea a mistaken one, 

 and by means of a series of diagrams and demonstra- 

 tions with the lantern he made out a strong case for 

 his view that flicker is due to the slightly varying 

 lengths of time during which the light from each 

 picture is transmitted to the screen through the open- 

 ings in the sector shutter. If the opaque portions of 

 the shutter are not all exactly equal, the eye, being 

 extremely sensitive to slight 'variations of 'illumina- 

 tion, receives the impression of alternating light and 

 darkness corresponding to the difference between the 

 angular size of the blades of the shutter sectors. 

 From this point of view the flicker should be com- 

 pletely eliminated by using any simple shutter with 

 four, three, or even two wings, the essential feature 

 being that the_ wings must all be very accurately made 

 of the same size. Various forms were shown in the 

 lantern projector; in practice the three-bladed sector 

 shutter is found most suitable. 



Another feature embodied in the " .Aeroscope " 

 camera is its adaptability for use without a tripod 

 stand, thereby greatly extending the scope of its use- 

 fulness to the portraying of scenes quite inaccessible 

 to the ordinary camera requiring a steady support. 

 The camera is fitted with self-contained mechanism 

 for driving the film, consisting of a small air motor, 

 driven by compressed air stored in four steel reser- 

 voirs held in the camera body. These cylinders can 

 be recharged by means of a cycle pump to a pressure 

 of 400 lb. per sq. in. The "motor is fitted with a 

 governor for keeping the motion of the mechanism 

 uniform, and a lever control on the exhaust for secur- 

 ing different values of this motion to suit different 

 subjects. 



The chances of injurious vibration during; the expo- 

 sure of the film are very neatly minimised bv the 

 introduction of a heavy gyrostat wheel in the end of 

 the camera box ; this is also driven from the air motor. 



.-\ series of beautiful pictures of scenery, including 

 animals and moving- water, taken bv Mr. Cherry 

 Kearton in North America, was sufficiently convincing 

 as lo the efficiency of this novel method of animated 

 pic-ture photography. C. P. 15. 



NO. 2261, VOL. 90] 



THE NATIONAL PHYSICAL LABORATORY. 

 \A,'ITH the view of raising funds to complete the 



*' additions now in progress at the laboratory, 

 the executive committee of tlie laboratory last autumn 

 appointed a funds committee, with Sir W. H. White 

 as chairman, and entrusted it with the task of appeal- 

 ing for support to persons interested in their national 

 work. 



This work was commenced at Teddington in the 

 year 1901 ; the great need of an institution such as 

 the laboratory and the importance of its work have 

 been amply demonstrated by its rapid growth. The 

 original buildings comprised Bushy House, granted 

 by the Crown, and an additional building for the 

 engineering department. The wide scope of the work 

 at the present time will be sufficiently indicated by 

 an enumeration of the various buildings, and a brief 

 indication of the purposes for which they are intended. 



(i) Bushy House, providing accommodation for 

 administration offices and for divisions dealing with 

 electrical units and standards, general electrical 

 measurements, thermometry, optics, and tide-predic- 

 tion. 



(2) Engineering building, for general engineering 

 research and tests, with additional accommodation for 

 aeronautical investigation, and for the examination of 

 road materials (Road Board Laboratory). 



(3) Metallurgy building, for investigations into the 

 properties of metals and alloys. 



(4) Electrotechnics building, equipped for researches 

 connected with electricity, and for the testing of alter- 

 nating- and direct-current instruments of all kinds, 

 as well as of material for electrical purposes ; also for 

 photometric work, especially the standardisation of 

 sources of light. 



(s) Metrology building, for measurements of length, 

 end gauges, cylindrical gauges, screw gauges, tapes 

 and wires for survey work, &c., the standardisation 

 of weights, and the testing of measures of area and 

 volume, glass vessels, &c. 



(6) William Froude National Tank, for experiments 

 on models of ships. 



(7) Observatory Department. This section of the 

 work has been housed at Kew Observatory, and in- 

 cludes the testing of thermometers, optical instru- 

 ments such as telescopes, binoculars, sextants, theo- 

 dolites, &c., watches, chronometers, and many other 

 types of instruments. 



To provide for the research work which is con- 

 tinuously in progress, and occupies perhaps two-thirds 

 of the time of the scientific staff, generous assistance 

 has been afforded by many private individuals, by the 

 City companies, and by all the great technical insti- 

 tutions, some of which have made annual grants for 

 this purpose for many years past. 



Some three years ago it was evident that further 

 buildings were needed at Teddington. The accom- 

 modation for the metallurgical work was then quite 

 inadequate, while tlie office and administration rooms 

 were entirely unsuited to their purposes. The library 

 had long overflowed the small room allotted for its 

 use ten years ago. The arrangements for the receipt 

 and dispatch of goods remained much as at the 

 beginning, and it had become increasingly difficult 

 to deal with the apparatus and materia! sent for test. 



Moreover, the optical and thermometric test work 

 at Kew has quite outgrown the opportunities for test 

 at the old observatory, and modern demands require 

 a revision of the methods and appliances available for 

 the work. In addition, a scheme has been approved 

 by the Royal Society and the Government for settin;,'- 

 free the observatory for mcteorolocjical observations 



