During the pre-Linnaean period, the beauty of insects - especially the Lepidoptera - had attracted a number of collectors; and these "Aurelians" - regarded as harmless lunatics by most of their friends - were the forerunners of the systematic students of later times.
The balloon carries two collectors a given vertical distance apart.
The action of the society in supplying practical instruction to intending travellers, in astronomy, surveying and the various branches of science useful to collectors, has had much to do with advancement of discovery.
Of flame collectors the two best known are Lord Kelvin's portable electrometer with a fuse, or F.
Flame collectors blow out in high winds, whilst water-droppers are apt to get frozen in winter.