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Spiral springs of quartz
548
CURRENTTOPICS.
[_J.F. I.
projection of the image of a luminous object by means of a spherical bicycle ball in place. of a lens. Each paint in the object throws a circular shadow of the bail having a white spot at its centre, and the aggregate of white spots forms the required image. Photographs can be reproduced by this method.” In the infra-red range of wave-lengths a spectrometer with a rock-salt prism is exhibited. By turning the prism all wave-lengths present that are in the interval from 5000 to IOO,OOOA. can be made to fall in turn on a thermopile and thus announce their presence. By this means a Bunsen burner shows itself to emit strongly radiation of #,OOO A. Among geophysical apparatus is a seismograph that is so sensitive as to show the tilt of a coast when subject to the weight of a tide. G. F. S. Spiral Springs of Quartz. K. SLIUPAS and C. V. BOYS. (Nature, June 20, 1925.)-In connection with work on gravitation in the University of Lithuania, Kaunas, Professor Sliupas had need of a spiral spring of unusual delicacy and succeeded in his first attempt to make one from a thread of fused quartz. Three centigrams gave an extension of no less than a centimetre. The method employed is described. A4n oxy-acetylene flame was used to melt the quartz. That prince of manipulators, C. V. Boys, tenders his congratulations upon the Lithuanian achievement, saying that in the late eighties of last century he tried to make a quartz spiral but failed. He describes a method by which he succeeded in producing a satisfactory spiral of glass thread. In Nature (July 3, 1925), H. Greville Smith, of Bristol University, England, gives an account of his experience in making quartz springs. The Silica Syndicate has made a considerable number of such springs, having 15 to 30 coils from .5 to 1.5 cm. in diameter. Springs of these dimenThe fibre was I or .2 mm. in diameter. sions will support a total load of .8 gram and stretch 9 mm. upon the addition of .I gram. They are thus more sensitive than the first spring of Professor Sliupas. He states, however, that this was greatly exceeded in delicacy by some of his later springs. Mr. H. D. H. Drane, in Nature (Aug. 29, 1925), gives details of a method of making springs from quartz fibres of about .OOI cm. The fibre, originally straight, is wound about a quartz tube diameter. to which both of its ends are attached. Thus constrained it is heated for a short time at a temperature above the annealing point of fused quartz. For the d#iameter given above one minute at I 100’ C. suffices. The coiled spiral then permanently assumes that form and keeps it after removal from the tube. By this process very sensitive springs can be prepared. One such spring was extended by its own weight G. F. S. at the rate of 30 km. per gram.
CURRENTTOPICS.
[_J.F. I.
projection of the image of a luminous object by means of a spherical bicycle ball in place. of a lens. Each paint in the object throws a circular shadow of the bail having a white spot at its centre, and the aggregate of white spots forms the required image. Photographs can be reproduced by this method.” In the infra-red range of wave-lengths a spectrometer with a rock-salt prism is exhibited. By turning the prism all wave-lengths present that are in the interval from 5000 to IOO,OOOA. can be made to fall in turn on a thermopile and thus announce their presence. By this means a Bunsen burner shows itself to emit strongly radiation of #,OOO A. Among geophysical apparatus is a seismograph that is so sensitive as to show the tilt of a coast when subject to the weight of a tide. G. F. S. Spiral Springs of Quartz. K. SLIUPAS and C. V. BOYS. (Nature, June 20, 1925.)-In connection with work on gravitation in the University of Lithuania, Kaunas, Professor Sliupas had need of a spiral spring of unusual delicacy and succeeded in his first attempt to make one from a thread of fused quartz. Three centigrams gave an extension of no less than a centimetre. The method employed is described. A4n oxy-acetylene flame was used to melt the quartz. That prince of manipulators, C. V. Boys, tenders his congratulations upon the Lithuanian achievement, saying that in the late eighties of last century he tried to make a quartz spiral but failed. He describes a method by which he succeeded in producing a satisfactory spiral of glass thread. In Nature (July 3, 1925), H. Greville Smith, of Bristol University, England, gives an account of his experience in making quartz springs. The Silica Syndicate has made a considerable number of such springs, having 15 to 30 coils from .5 to 1.5 cm. in diameter. Springs of these dimenThe fibre was I or .2 mm. in diameter. sions will support a total load of .8 gram and stretch 9 mm. upon the addition of .I gram. They are thus more sensitive than the first spring of Professor Sliupas. He states, however, that this was greatly exceeded in delicacy by some of his later springs. Mr. H. D. H. Drane, in Nature (Aug. 29, 1925), gives details of a method of making springs from quartz fibres of about .OOI cm. The fibre, originally straight, is wound about a quartz tube diameter. to which both of its ends are attached. Thus constrained it is heated for a short time at a temperature above the annealing point of fused quartz. For the d#iameter given above one minute at I 100’ C. suffices. The coiled spiral then permanently assumes that form and keeps it after removal from the tube. By this process very sensitive springs can be prepared. One such spring was extended by its own weight G. F. S. at the rate of 30 km. per gram.