6 Eminent Living Geologists — 



regard to the rain-gauges and the percolation gauges which had been 

 started at Nash Mills in 1836 by his uncle John Dickinson, and had 

 been in continuous operation under his own direction since 1853. 

 Sir John Evans brought the subject before the Institution of Civil 

 Engineers in 18S5 in a lecture on " Physiography," one of a series, 

 given by distinguished observers, on " The Theory and Practice of 

 Hydro-mechanics." 



In his evidence in 1892 he stated that the average percolation for 

 thirty-seven years through 3 feet of soil, on which grass was allowed 

 to grow, was 7"55 inches, and through 3 feet of chalk 10-71 inches; 

 the yearly average rainfall being 27*42 inches. He felt it unsafe, 

 however, to calculate on a certain supply of more than 4 inches of the 

 rainfall, whether from the springs or streams of such a district as the 

 Chalk of Hertfordshire, because many vegetable roots penetrate the 

 earth to a far greater depth and absorb moisture, and in dry seasons 

 moisture can be brought from a greater depth in Chalk by means of 

 capillary attraction. Sir John Evans also dealt with the etfect on the 

 streams of pumping water from the Chalk.' 



Sir John Evans has on several occasions acted as a guide to the 

 Geologists' Association, having conducted or taken part in the con- 

 ducting of excursions since 1875 to Watford, Tyler's Hill, Chesham, 

 and Berkhamsted. 



He has an extensive knowledge, not only of prehistoric archaeology, 

 but also of ancient, especially British gold coins, and of engraved gems. 

 More than this, though he left school so early, he is a really good 

 classical scholar, besides being well versed in at least three modern 

 languages. Few men have shown more conspicuous ability in transacting 

 the business of societies. His experience of life and affairs, as manager 

 of an important commercial undertaking, as a county magistrate, as 

 member or chairman of committees of different kinds, make him 

 invaluable in any official position. He was three times a member 

 of the Council of the Royal Society — on the last occasion for a penod 

 of twenty years as its Treasurer. In that office he rendered great 

 service to the Society in bringing its financial affairs into a satisfactory 

 condition, and his advice on the various and sometimes difficult 

 questions brought year by year in increasing numbers before the 

 Society was always of the highest value. In 1884, in conseqiience 

 of the illness of Professor Huxley, P.R.S., he delivered the Anniversaiy 

 Address. Of the Geological Society he was Secretary from 1866 to 

 1874, President from 1874 to 1876, and Foreign Secretary from 1895 

 to the present date, besides being a member of the Council and Vice- 

 President on other occasions. Of Sir John Evans's long connection 

 with the Society of Antiquaries and his communications to that body 

 on subjects which have no bearing on geology this is not the place to 

 speak. With regard to the Royal Numismatic Society, which he 

 joined in 1849, it may be mentioned that he has been since 1860 one 

 of the Editors of the Numinmatic Chronicle^ which is now completing 

 its 47th volume. In 1878-9 he was President of the Anthropological 

 Institute. In 1893 he was Chairman of the Society of Chemical 



' See his second Presidential Address to the Geological Society (Geol. Mag., 

 1876, pp. 185-186), 



