THE CHAIRMAN Mr Sidney Arthur Main, B Sc, is a distinguished engineer andscientist He takes a prominent part in the Research Laboratories of MessrsHadfields, Ltd, Sheffield With Sir Robert Hadfield he was joint author of thepaper on “Shock Tests and their Standardisation,” read before theInstitution of Civil Engineers in 1921, and for this paper that Institutionawarded him the “James Watt” Gold Medal

During recent years general interest in Heat-Resisting Steels has grownconsiderably, and there is a wide field for their application in aeronauticalengineering However, little has been published with regard to the more complexnoncorrodible and non-scaling steels, and it is a matter of satisfaction thatthis Institution has been able to secure a paper on the subject by such aneminent collaborator of Sir Robert Hadfield, as the present lecturer

I now have much pleasure in calling upon Mr Main to deliver his paper

BEFORE presenting to you a description of the activities in applying insecticidesby aeroplane, I wish to acknowledge the assistance of the U S Department ofAgriculture, to whom I am indebted for the early history of this branch offlying, and to also acknowledge quotations from a report on the subject by ProfA D Imms, M A —

Early Experiments

I believe it correct to state that the possibility of applying insecticides bymeans of aeroplanes, was first brought to public attention by the work conductedin August, 1921, by the State Experimental Station of Ohio

This particular test, consisted of distributing lead arsenate from an aeroplaneover a grove of catalpa trees, in an effort to poison the larvæ of thecatalpa sphinx (ceratomia catalpæ Bdv) which were defoliating thegrove