;o6 



NATURE 



[December i6, 1920 



ia 



principle of a bubble sextant is shown diagram- 

 matically in Fig". 4. By means of a lens and prism 

 (not shown), which ire 

 fixed above the bubble 

 lens, the horizon can also 

 be seen in the field of 

 view, as well as the 

 bubble, so that the instru- 

 ment may be used as an 

 horizon sextant if 'e- 

 cjuired. 



The problem of the 

 rapid calculation of sex- 

 tant observations appears 

 to have been solved com- 

 pletely by the cylindrical 

 slide-rule due to Mr. 

 Bygrave. With a slide- 

 rule about 7 in. long re- 

 sults can be obtained in 

 three or four minutes' 

 time which are accurate to 

 within about three 

 minutes of arc. , With 

 larger patterns greater 

 accuracy in obtained. 



The accompanying illustrations are from a 

 lecture on "The Design of Instruments for the 



Navigation of Aircraft," read to the Royal Geo- 

 graphical Society by the author on May 10 last, 



^^) 



fa-%^'' — 



SuBBL-C LEMS - 



( fl)EH15I<-— >, 



5<lvg-gd Fac« 



Fig, 4. — R.A.E. bubble sextant Mark U. «, axis about which clear mirror ^ is moved by pin ^ resting oa 

 cam c fixed to drum d. Imase of bubble in lens cell^ seen by reflection in e through lensy"aft«T further 

 reflection in prism /. Bubble illuminated at night by lamp /. 



and published in the Geographical Journal for 

 November. 



Industrial Research Associations. 



VT. — The Glass Research Association. 

 By Edward Quixe. 



rHE Glass Research Association has been estab- 

 lished for investigation into the problems of 

 the glass industry in accordance with the scheme 

 of the Committee of the Privy Council for Scien- 

 tific and Industrial Research. The association 

 received its Certificate of Incorporation on 

 August II, 1919, and held the first general 

 meeting on October 14 following. 



The objects of the association are to conduct 

 scientific and technical investigations relating to 

 glass and its manufacture, and to disseminate 

 among members technical and other information 

 bearing on these subjects and on the production 

 of articles made wholly or partly of glass. 



The rate of development of the glass industry 

 in this country is largely influenced bv difficulties 

 in the matter of technique, works organisation, 

 production and equipment, and, in order that the 

 industry may attain a high degree of efficiency, it 

 is necessary for investigations to be directed to- 

 wards overcoming these difficulties, in addition to 

 investigations of fundamental principles and search 

 for new knowledge. To ensure that greater 

 economy in production and more satisfactory pro- 

 ducts may be obtained, improved methods must 

 be introduced, and the works practice of the in- 

 dustry brought into line with the advanced 

 methods found operative in other countries. Until 

 recent years no comprehensive research work re- 

 NO. 2668, VOL. 106] 



lating to the industry had been carried out in this 

 country, but the need for a deeper and more ex- 

 tensive knowledge of the fundamental facts under- 

 lying the various processes of manufacture is now 

 appreciated. The association is consequently en- 

 deavouring to secure that the fundamental prin- 

 ciples and their application shall be thoroughly in- 

 vestigated by systematically conducted researches, 

 so that, side by side with the modernising of 

 works practice, and the introduction into the in- 

 dustry of the scientific control of the various 

 operations, new knowledge may be acquired 

 which may ultimately lead to industrially valuable 

 developments. 



The investigations of the association cover the 

 problems of all sections of the glass industry 

 other than those of optical glass, research 

 work in which is being undertaken by the 

 British Scientific Instrument Research Associa- 

 tion. 



The membership of the association is limited 

 to British corporations and British subjects carry- 

 ing on business in connection with the manufac- 

 ture of glass, and other trades and industries 

 allied therewith or accessory thereto. Individuals 

 ineligible for membership or not desiring admis- 

 sion as members, who are interested in the glass 

 industry and willing to subscribe to the objects of 

 the association, mav be admitted bv the council as 



