Trmmtion Studies 



Fig. 1 (p. 1 8) explains, of course without the detailH, Gallon's idea. I do not 

 know whether it was ever dealt with exjK'riinentally ; the extreii ' "it 

 trajectories of modern bullets, the fact that A would have to prote< ' If 



not against a single rifleman at a definite range B, but against a numlx^r of 

 riflemen in different and ordy vaguely known |>OHitions, tells against the 

 method. ?2ven in the case of a single opponent li, tiie latter might, by 

 shifting his position somewhat, actually use A's protection as a protection 

 for himself Still it is conceivable that the metluKl might be of service in 

 trench warfare, when the ground in front had been accunitely ranged, and the 

 danger of drawing artillery fire by the screen had been if |K>88ible overcome. 



Gallon's other paper, namely on the heliostat, is of more direct interest as 

 indicating the mechanictil l)ent of his niind. He had been interested in helio- 

 static work since his Long Vacation reading party at Keswick in 1841 when he 



N 



Fig. A. From Qalton's original drawings for liis heliostat. Diagrammatic figure indicating how the moek-tan 

 18 formed and seen covering a portion of the field of view at V. The small screen A' only intercept* a imall 

 portion of the field of view. Cf. Fig. 1, p. 20. 



Fig. B. From Oalton's original drawings for his heliostat. Field of view of the 

 telescope with the mocksun covering the point of a promontory to which 

 the instrument would flash light. 



found on the top of Scawfell a party of ordnance surveyors endeavouring to 



get into touch with Snowdon and obtain its bearing by aid of a heliostat'. 

 ralton's ambition was to construct a pocket heliostat and he spent much 

 time in preparing models, of which the Gallon Laboratory possesses almost 



Menuyriet, p. 61. 



3—8 



