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34

 

Life and Letters of Francis Galton

 

(2)

The Ortler group of mountains, from an Austrian model.

 

(3)

Mount Blanc district, from Bauerkeller's relief map.

 

(4)

Cape Town and Table Mountain, from a coloured model.

 

5)

Abyssinia, from a rude nodel.

 

6)

The Isle of Wight, from a rude model.

The paper itself is accompanied only by a photograph of (1)', somewhat confusing as it illustrates also the proposal of Galton to build up large maps in stereoscopic sections.

The Galton Laboratory possesses stereoscopic slides of (1) giving the whole island, and of (2)-(6) inclusive, and also of a seventh slide-part of the Ile de Porquerolles in the Mediterranean off Toulon.. Our photographs have faded in the course of nearly sixty years but they show still with extraordinary effect the success of Galton's idea. The Stelvio stands out in a way that no map can compete with, and hardly a bird's-eye view from the Spitz itself could give such a good conception of the `lie of the land.' It is a grievous pity that the stereoscopic idea of map-models has been forgotten, and we might hope for its resuscitation in association with the air-plane as already suggested. We provide in the accompanying plate copies of the faded photographs of (1) and (2) which nevertheless will suffice-if the reader be lucky enough to possess a pair of stereoscopic lenses-to justify this statement.

Another paper of this same year is entitled: "Spectacles for Divers and the Vision of Amphibious Animals." In this paper Galton states that if water is in contact with the human eye' a double convex lens of flint glass, each of whose surfaces has a radius of 0.48 inch, will correct the concave water lens. It will require to be supplemented by another of moderate power according to the convexity of the individual eye and refractive power of the different kinds of flint glass. Galton found, however, that even with a lens of this kind under water the eye had not much power of accommodating itself to different distances, and his own distinct vision was restricted to a range of about eight feet. He considered, however, the glasses he used only provisional'. He thought such spectacles might be useful to divers in pearl and sponge fisheries, or to sailors examining the bottoms of ships. The paper suggests that amphibious animals must have a power of adjusting their sight, i.e. seals, otters, diving birds, etc., but does not enter into the modus operandi. Here again as in the case of stereoscopic maps I think an interesting question has failed to be carried further.

As late as 1881 Galton still maintained some interest in geographical research, but his main work was directed into other and more congenial channels. In the British Association Report, 1881`, there is a brief comparison by Galton of the equipment of exploring expeditions in 1830 and 1880. He notes the progress that has been made in certain instruments

' Search at the Royal Geographical Society having failed to discover the originals, a further hunt among the negatives of the Galtoniand has brought to light the originals-too late for reproduction here.

2 B. A. Report, Vol. xxxv, 1865 (Sect.), pp. 10-11, not as when the diving helmet is used. 3 Still extant in the Galtoniana.   4 pp. 736-40.