474 Mr. W. 0. D. Whetham on the 



The Sun becomes a globe 14 centims (nearly 5^ inches) 

 across. Putting this at the centre, the earth is a grain of the 

 smallest snipe-shot at the distance of 15 metres, attended by 

 the moon (a minute bead) nearly 4 centims off: the whole 

 Solar system is comprised within a sphere which has a kllem 

 for its diameter ; and the distance upon the same scale of the 

 nearest star is 4000 kllems (2500 miles). 



A year is represented by 5£ minutes (more exactly, 

 315*567 seconds), in which time the grain of shot is to 

 describe its revolution round the Sun ; a day becomes 

 0"864 of a second, in which time the grain of shot is to turn 

 upon its axis. The earth's velocity in its orbit round the Sun 

 is nearly 30 kllems per second. This, upon the model, becomes 

 a speed of 30 centims, or one foot, per second ; and if the grain 

 of shot travels along its orbit at this pace it will get round it 

 in the 5^ minutes that represent a year. The relative velocity 

 of the moon in its orbit round the earth is nearly one kllem 

 per second, so that the bead that represents the moon is to 

 advance along its little relative orbit, which is about the size 

 of the palm of one's hand, at the rate of one centimetre per 

 second. Upon the same scale the velocity of light becomes a 

 speed of 3 kllems per second, which is more than twice the 

 speed of the swiftest projectiles of modern artillery. We are 

 to imagine that waves of telegraphy travelling at this high 

 speed, till all the intervening space and keep up a constant 

 communication between the several bodies of the Standard 

 Model. 



It would be convenient if all astronomical diagrams were 

 constructed on scales which bear some simple relation to the 

 Standard Model of the heavens. This was attempted in the 

 author's diagram of the orbit of the November meteors (the 

 Leonids), which has been copied into many books on astronomy. 

 It was intended that the diagram should have been on a 

 scale exactly one 5000th part of the Standard Model, but 

 as engraved it differs from the intended scale by about one 

 thirtieth part. (See the Royal Dublin Society's Journal for 

 1869, or the Proceedings of the Royal Institution for 1879, 

 in either of which the original diagram will be found.) 



XLIX. The Coagulative Power of Electrolytes. ByW.O.T). 

 AYhetham, M.A., Fellow of 'Trinity College, Cambridge*. 



IT has been found that electrolytes possess the property of 

 coagulating solutions of colloidal bodies such as albumen 

 and arsenious sulphide, and that their relative coagulative 

 powers depend in a very striking manner on the valency of 

 the metallic ion. 



* Communicated by the Physical Society. 



V. 1% . M1 - 



+ u 7T\a- 



