280 f/ij'e (tin/ Lettcrit of Francis Galton 



near approach to the earth, and that the poasihiUty of exchanging signals 

 with Mars was then discussed in the newspapers; it was considered not 

 impossible, if enormously difficult, to send signals. But there was a 

 general conclusion that if sent, the only thing tliat could he learnt from 

 them would be that there existed observant, intelligent and mechanical 

 people Ciipable of great enterprises on the other planet. Oalton thought 

 that much more miglit be aciiieved, and that an iutrinniatUi/ intelligible 

 system of signals could be devised, if the people on the other planet were 

 equally advanced with ourselves in pure and applied science. He amused 

 himself accordingly in tliinking out the ground plan of the present paper, 

 but laid it aside for four years during which the craze about Mars died 

 out, "l)eing cooled by coj)ious douches of astronomical common sense." Then, 

 in 1896, came an attack of giistric catarrh, wliicli developed into more serious 

 trouble owing to a visit to Kew — to attend the Observatory— with a tem- 

 perature of 102. Galton was invalided to Wildbad and its hot baths, and amid 

 their relaxing accompaniments, being able to work only in a desultory Ihshion, 

 he wrote up his pa})er on signals from Mars'. The mam point of this paper is 

 the building up of a system of signals from which ultimately pictures can be 

 constructed. It is half humorous and half serious. It starts with the idea 

 that arithmetical and mathematical notions will be common knowledge of 

 both planet's inhabitants. Signals of l\, 2^ and 5 seconds are given and 

 termetl dot, dash, line. These lead up to a system of numerals. Then 

 comes the ratio of the circumference of a circle to its diameter, the value of 

 the familiar n. Thence the ratio of the circumference to the radius of the 

 various regular jwlygons, which introduces signals for the polygons. The 

 24-sided regular polygon is then indicated jus a method of direction, and 

 so angles all round the 360° are gradually learnt in the .same way as are the 

 points of a compass, but direction of lines and length of lines being given it 

 becomes possible to give signals indicating a picture by successive "stitches" 

 of definite lengths in definite directions. That is to say, Galton has reached the 

 picture formula of his lecture on the "Just Perceptible Difference" (see the 

 following Chapter, p. 307). But once it is possible to signal pictures, all 

 becomes po.ssible. It becomes possible to indicate motion, and motion will 

 enable one to indicate signals for action, i.e. verbs. Such, very briefly, is 

 the outline of Galton's system of star signals : 



"It would be tedious, and is unnecessary to elalxirato further, for it must be already 

 evident to the reader that a small fraction of the care and thoufjht l>estowe<l, say, on the 

 deci|>hennent of hieroglyphics, would suOice to place the iiihaliitants of neighbouring stars in 

 intt'lligihle communication if thej' were l»oth as far advancwl in science and arts as the 

 civilise*! nations of the earth are at the present time. In short, that an efiicient intci-stellar 

 language a^hnitt* of lieing esLahlished under these conditions, between stars that are sufiiciently 

 near together for signalling purposes." 



' Both Oaltons were much deprcssefl during this year. Emily Gurney died, and Sir William 

 Orove diwl on the anniversary of the Gallons' wedding day (August 1st). The season whs very 

 wet and Galton suflerwl much from colds; he complaine<l for the first time (agetl 74!) that 

 his brain power was not as vigorous as formerly, that he could not work quickly and that his 

 deafness interfered with his committoes. 



