. Automotive industries . s has developed anew method for producing very small and lightmirrors for use on oscillographs. Some time ago an at-tempt was made to produce these mirrors from aluminum,polishing the metal in the usual way. However, it wasfound that the metal was too soft to be satisfactorilypolished and some other means had to be devised whichwould give a better and at the same time as light a process, as finally worked out, consists in pressing thealuminum between two optically flat steel dies. Themirrors thus made are highly polished with the surfacessufficiently plane
. Automotive industries . s has developed anew method for producing very small and lightmirrors for use on oscillographs. Some time ago an at-tempt was made to produce these mirrors from aluminum,polishing the metal in the usual way. However, it wasfound that the metal was too soft to be satisfactorilypolished and some other means had to be devised whichwould give a better and at the same time as light a process, as finally worked out, consists in pressing thealuminum between two optically flat steel dies. Themirrors thus made are highly polished with the surfacessufficiently plane to produce satisfactory images of thespot of light. The dimensions of the mirrors so far pro-duced are approximately 5 L> mm. wide, 1% mm. long, to .20 mm. in thickness. Care must be taken not touse too much pressure, as then the resulting mirror isso thin that it will not retain its plane surfaces. March 10, 1921 AUTOMOTIVE INDUSTRIES THE AUTOMOBILE 555 Examples of Finish Used on Top Edge of European Car Bodies. 556 AUTOMOTIVE INDUSTRIESTHE AUTOMOBILE March 10, 1921 Rust Prevention by Browning Process Has been used extensively for many years for treating component partsof small arms. Produces a bluish black finish which is rendered dullby sand blasting or may be polished by buffing. Finish does not ruboff, is not easily scratched and resists rust to a marked degree. Specifi-cations for preparation of solutions and methods of application are given. By W. C. Marshall* IN looking over the back numbers of a prominent auto-mobile periodical recently, the writer came across anarticle on rust prevention and read it with great inter-est. Much to my astonishment, no mention was made ofthe Browning process, although the process is old and usedextensively by small arms manufacturers for treating bar-rels and component parts of small arms. Having been connected with the works of a companymanufacturing small arms in the capacity of research en-gineer, it fell to my lot to investi
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectaeronautics, bookyear
