The history of an invention, whether of science or art, may be compared to the growth of an organism such as a tree. The wind, or the random visit of a bee, unites the pollen in the flower, the green fruit forms and ripens to the perfect seed, which, on being planted in congenial soil, takes root and flourishes. Even so from the chance combination of two facts in the human mind, a crude idea springs, and after maturing into a feasible plan is put in practice under favourable conditions, and so develops. These processes are both subject to a thousand accidents which are inimical.
