PRESIDENT'S ADDRESS. 11 



still further from the sun, but, though its position may be 

 indicated, it is expected that it would be too faint to be visible. 

 From some faint asteroids discovered by photography at the 

 Lick Observatory it is estimated that the total number above 

 the 20th magnitude may amount to 57,000, whilst other con- 

 siderations suggest 100,000. These figures however seem to 

 do little more than shew that the number is probably very 

 large. Estimates of the age of the moon, that is to say the 

 length of time since it was thrown off from the earth, according 

 to the received theory, by different methods of calculation 

 vary from 60,000,000 to 1,200,000,000 years, shewing the great 

 uncertainty of these estimates. A meteorite which fell on 

 November 27th, was seen to descend into Lake Michigan; and 

 several meteors of more or less striking brightness have been 

 recorded, four at Bristol, on July 20th, October 22nd, 

 November 27th, and December 25th, one on October 21st at 

 Wimborne and elsewhere, another at Wimborne on November 

 2nd, one at London on January 16th, which left a trail which 

 lasted 5^ minutes, and one on February 4th seen in various 

 parts of the country, also on February 17th and 27th. The 

 recent new star, Nova Aquihe, which caused so much 

 astronomical interest in 1918, had faded to the 6th magnitude 

 in April, 1919. From a comparison at the Johannesburg 

 observatory of recent photographic plates with those taken 20 

 years ago, it has been found that no less than 400 stars, out of 

 the 20,000 shewn, have a measurable proper motion, the 

 amounts in this case varving from 290", 179" and 167" 

 downwards, only 75 being more than 20", all per 100 years. 

 Comparisons lately made between the distances of stars, as 

 calculated by spectroscopic and trigonometrical methods, 

 shew very satisfactory agreement. The new lOOin. reflecting 

 telescope at Mount Wilson has turned out very successful; and 

 some beautiful lunar photographs have been taken with it, 

 shewing very fine detail. An exhibition of early scientific 

 instruments was held at Oxford last year, when various 

 interesting astronomical and other instruments were shewn, 

 the earliest being a Persian astrolabe dated A.D. 987 and a 

 Moorish one of 1067. 



