50 years ago

“Marking of tsetse flies for their detection at night” — Most testse field-work so far has been based on day-time observations of active flies. If work is to be done on resting flies, it will be advantageous to have an easy method of locating them. It is known that mosquitoes can be dusted with non-toxic materials which fluoresce in ultra-violet light at night, and using this method, mosquitoes can be watched at a distance of about 10 ft. The insects are not sensitive to ultra-violet radiations... 'Dayglo' (silica-based organic dyes in ethyl cellulose) powders mixed with a binder and solvent produced a satisfactory paint and were used in a series of tests on house and tsetse flies... Paint was applied with a sharpened match-stick on the centre of the thorax, covering it without fouling head or wings. At 15 ft., treated flies shone brilliantly in the ultra-violet beam and the maximum range was 20 ft.

G. R. Jewell

From Nature 6 October 1956.

100 years ago

“The genesis of the inventor” (Erfindung und Erfinder by A. du Bois-Reymond) — The author's analysis of invention and inventors leads to the conclusion that neither need, nor chance, nor the lack of necessaries in surrounding life suffices to draw out the inventor. Instead of solving the problem by philosophic deduction from generalities, he descends to the particulars of the Patent Office, and concludes that inventors can be subdivided into three classes:— first, the intuitive genius, or, as Herbert Spencer would have said, the man who can do with little trouble that which cannot be done by the ordinary man with any amount of trouble; secondly, the technical man, well acquainted with his work, who follows in the wake of the intuitive genius, and is largely inspired by him; thirdly, the layman, whose special province seems to be feeding-bottles.

From Nature 4 October 1906.