324 



KNOWLEDGE. 



August, 1911. 



plates have accumulated one's thoughts turn to methods of 

 handling a larger number of plates at the same time than 

 would usually be eniployed and the ease with which several 

 plates can be developed in a tank is certainly one reason 

 for the popularity of tanl< development. Tank development, 

 however, introduces a number of possible difficulties which are 

 less likely to occur during development in a dish. In the first 

 place a tank should be selected which can be reversed or shaken 

 so that circulation of the developer can be assured, because 

 otherwise there is considerable danger of accumulations of 

 oxydised developer which may produce most unexpected marks 

 upon the plate. A photograph of a church tower against the 

 sky, for instance, which is left quiescent in a tank with the sky 

 downwards may show upon the prints a white mark extending 

 up into the sky from the tower. This is owing to the fact that 

 the developer on the face of the plate immediately over the 

 tower does no work, and consequently remains fresher than 

 the developer covering the rest of the sky, and this fresh 

 developer slouly streaming o\'er the sky immediately below 

 the tower produces a streak of greater density in the negative, 

 which appears light in the print. 



If a very dilute developer is used for prolonged development, 

 generally known as " stand " development, marks of obscure 

 origin are often met with and such a developer may gi\e rise to 

 a considerable amount of general fog. The reason for this 

 fogging by dilute developers has not hitherto been understood, 

 but some recent observations would appear to show that in some 

 cases, at any rate, it is due to the lowering of the sulphite concen- 

 tration in the developer, and may be removed by addition of 

 sulphite when the developer is diluted. .\ difficulty with 

 many developers when used for stand development, is that it 

 is impossible to calculate the time of development from the 

 dilution, because the reducer is oxidised by the air dissolved 

 in the water used. The dilution of one part of a metol 

 developer, for instance, with nine parts of water, will not give 

 a developer requiring ten times as long for development as the 

 original solution, but a longer period will be required, the 

 extension depending upon the air content of the water used 

 for dilution. A reducer, which appears to be almost entirely 

 free from this defect, and which, therefore, must be little 

 amenable to aerial oxidation, is glycin, which is pcculiarlv 

 suitable for timed development with weak solutions. 



PHYSICS. 



FRESH SUPPORT FOR PROFESSOR BICKEKTON'S 

 THEORY. — The conclusions of Professor Kapteyn's recent 

 address to the Dutch Science Congress, based on his own and 

 other observations, furnish a most remarkable case of the 

 fulfilment of physical deductions and predictions. 



For over thirty years Professor Bickerton, of New Zealand, 

 has with increasing emphasis been making cosmic dynamical 

 deductions and publishing papers and books, showing that 

 every characteristic of our Galaxy can be most easily 

 e.xplained by assuming that it is made up of two cosmic 

 systems, of different orders of development. Ages ago these 

 two systems interpenetrated one another, coalesced, and 

 swung off the double spiral of stars called the Milky Way. 

 The idea was very clearly shown in a paper in the Pit Ho- 

 sophical Magazine for .August. 1900. Kapteyn's conclusions 

 are as follows : — 



" The Stellar system was not originally a single system in 

 which the two known drifts or currents have developed ; but 

 the present system is the result of the encounter of two systems 

 which originally were entirely independent of each other." 



" The primordial matter is now more abundant in the drift 

 of less star-density, and is almost entirely absent from the 

 opposite drift which is richer in stars." 



Kapteyn's system of much primordial matter is Professor 

 Bickerton's cosmic system of the first order, which on 

 dynamical grounds he shows must grow up in the empty parts 

 of space. One of these primordial systems has interpene- 

 trated with one of a higher order. Such impacts, to quote 

 Professor Bickerton's paper in the Pliilosupliical Magazine, 

 will produce a cosmic system of a third order, of which our 

 Galactic .system is a type. 



For some years back, in Australasia, there has been growing 

 up a belief that this new cosmogony is true, as it has anticipated 

 in a remarkable way so many subsequent discoveries. This 

 belief has culminated in the New Zealand Government sending 

 Professor Bickerton to England to present it as a working 

 hypothesis to guide astronomical research. 



In our next number Professor Bickerton will tell the story 

 of Nova Persei, the new star of the new century, that in less 

 than two days grew from invisibility, to be actually the 

 brightest star in the Northern Hemisphere. Had the flash of 

 this temporary star been seen at the same distance as our Sun. 

 this huge celestial light would have been ten thousand times 

 as bright a blaze as the Sun itself. Professor Bickerton says 

 that all new stars are the explosively hot third bodies, torn 

 from grazing suns. The surprising number of phenomena that 

 were scientifically deduced, as possessed by this vast cosmic 

 spark, a score of years before Nova Persei appeared, and the 

 complete way .all have been demonstrated by astronomers, 

 reads more like a fairy tale than a statement of sober fact. 



SEISMOLOGY. 



A SEISMOGRAPH ATA LONDON ICNHUJITION.— At 

 the Coronation PIxhibition. Shepherds Bush, there is this year 

 one very interesting sight — a seismograph actually at work. 

 The exhibitor is Mr. J. J. Shaw, of West Bromwich, and he 

 believes that this is the first time that a seismograph has ever 

 been publicly exhibited under working conditions. He has 

 been fortunate in that, during June, two large earthquakes 

 occurred and were recorded by his instrument. 



Mr. Shaw's instrument differs in several details from Pro- 

 fessor Milne's well known pattern which has been adopted as 

 the standard form by the Seismological Section of the British 

 .Association. The two horizontal pendulums are suspended 

 from separate brick columns and actuate multipl>-ing levers 

 which by means of glass needles record the movements on a 

 smoked paper roll carried on a revolving drum. These 

 two records are marked side by side with the time record 

 between them. This is, for popular demonstration purposes, 

 a method superior to that adopted by Professor Milne, whose 

 instruments give photographic records which require to be 

 developed before they become visible. 



A record on the Seismograph, at the exhibition, of an earth- 

 quake in Mexico on June 5th, is only the second that has been 

 made on any instrument in London. 



ZOOLOGY. 



THE FLYING APPARATUS OF THE BLOWFLY.— 

 Dr. Wolfgang Ritter describes in Smithsonian Miscellaneous 

 Collections, Volume 56, No. 12, his researches upon the 

 flight of an insect. He finds that the downward movement of 

 the wings is caused by the contraction of two powerful dorsal 

 muscles, and he has repeated an old experiment illustrating 

 this. From a recently-killed fly, whose wings are raised, the 

 abdomen and head are removed and the thorax grasped with 

 a broad pair of forceps, so that one part of the latter is at its 

 anterior, and the other at its posterior end. On compressing 

 the forceps the thorax is shortened just as it is when the dorsal 

 nmscle contracts and the wings descend. The dorsi-ventral 

 muscles act as antagonists to the dorsal, and by compressing 

 the thorax in a vertical direction, raise the wings. A direct 

 muscle brings the wings back from the position of flight to 

 that of rest. Other direct muscles, which probably act as 

 steerers, draw the wings respectively forward and backward 

 and depress various portions of it. 



THE SPIRIT BUILDINGS Al lUL BRITISH 

 MUSEUM (Natural History). — It has been announced that 

 an amicable settlement has been arrived at between the 

 Trustees of the British Museum and the Office of Works with 

 regard to the site for the Science Museum, for which the 

 ground now occupied by the Spirit Building, with its important 

 collections of zoological specimens in alcohol, was demanded. 

 No further official information is forthcoming, but it is said 

 that the arrangements that have been made will obviate the 

 necessity of pulling down the building in ijuestion. 



