328 THE BINARY STARS. 



hope to see. It is noteworthy also that in all this the distance of 

 the Algol system from the earth is of no account, and in no way 

 enters into or affects the calculation. 



It has also been possible to weigh Algol and his companion, 

 and ascertain their masses, in the same way as the masses of other 

 binary stars have been discovered, and we are assured that though 

 Algol is about twice as big as the sun (that is to say, has about 

 twice the sun's bulk), yet he is made of much lighter materials, as 

 he only weighs about half as much, and the companion, though 

 about the same size as the sun, only weighs about one fourth of 

 the sun's weight. 



Sir Robert Ball has drawn attention to the (as he terms it) 

 monstrous proportion which exists between the sizes of Algol and 

 his companion, and their distances apart, as compared with dimen- 

 sions and distances in the solar system ; for, whereas Algol is about 

 a million miles in diameter, and his companion about 800,000 

 miles, yet they are only about, in round numbers, three million miles 

 apart from centre to centre • and I will conclude my paper by 

 borrowing one of Sir Robert Ball's illustrations for you to remem- 

 ber the relative sizes and distance apart of Algol and his compan- 

 ion by ; and this is, that if we take a shilling to represent Algol 

 and a sixpence to illustrate the size of his companion, and place 

 them so that their rims are two inches apart, they will fairly 

 represent, with regard to relative sizes and distance apart, the 

 proportions of this wonderful and interesting Algol system. 



Arctic Hail and Thunderstorms. — Mr. H. Harries read a 

 paper before the Royal Meteorological Society on June 17th, 1896, 

 on " Arctic Hail and Thunderstorms," in which he showed that 

 the commonly-accepted opinion that hail and thunderstorms are 

 almost, if not quite, unknown in the Arctic regions, is incorrect. 

 He had examined a hundred logs of vessels which had visited the 

 Arctic regions, and found that out of that number no fewer than 

 seventy-three showed that hail was experienced at some time or 

 another. Thunderstorms were not so frequent as hail, but they 

 have been observed in seven months out of the twelve, the month 

 of greatest frequency being August. Mr. Harries is of opinion 

 that the breeding place of thunderstorms in these high latitudes is 

 in the neighbourhood of Barent's sea. — Science. 



