SCIENCE- G OS SI P. 



285 



1877, and as lately as in Christmas week 1901 

 whilst at Enfield. Perhaps the most interesting 

 effect of the brilliance is, that Professor W. R. 

 Brooks has actually succeeded in taking photo- 

 graphs by the light of the planet. 



Monthly Star Maps for 1902. — These com- 

 pilations by Mr. W. B. Blaikie have been sent to us 

 included in the useful blotting-book issued by the 

 Scottish Provident Institution. They are most 

 interesting and useful for showing the varying 

 positions of the constellations month by month, 

 and the daily place of the Moon. The situations of 

 Jupiter and Saturn, the only planets visible in the 

 10 o'clock sky, are shown on the maps. There 

 is also a chapter explaining the apparent motions 

 of Venus, besides an abundance of useful informa- 

 tion for the amateur observer. 



John J. Brett, F.R.A.S. — We are sorry to have 

 to record the death of this well-known artist and 

 astronomer of Putney. A fine lunar sketch from 

 his pencil illustrated the first number of " The 

 Observatory." 



compared with the sky, which meant a vast amount 

 of patience. No further discoveries, however, 

 were made until December 1845, when Hencke, 

 of Driessen, who had been diligently searching for 

 fifteen years, discovered Astraea. Since 1847 no 

 year has passed without one at least of these pigmy 

 worlds being found. Goldschmidt, labouring with a 

 2i-inch telescope from a window near Paris, dis- 

 covered fourteen. So far back as 1859 Mitchell, 

 of Cincinnati, wrote :— " Could a daguerreotype 

 picture of any region in the heavens be made 

 to-night, and at the end of a year another picture 

 of the same region could be taken, by comparing 

 the number of stars in the one picture with that 

 in the second ... it would be an easy matter to 

 ascertain " the coming or going of strangers. Not, 

 however, was it until the end of 1891 that Pro- 

 fessor Max Wolf, of Heidelberg, when photo- 

 graphing stars in the ecliptic, found amongst the 

 stars two short lines or trails. One of these was 

 proved to be produced by the planet Sapientia, 

 already known, and the other by a new planet, 

 No. 323, afterwards named Brucia. Since that 



Minor Planets. — Print from Photographic plate showing Trail by which Svea, No. 329, was discovered. 

 {By permission of Professor Max Wolf.) 



CHAPTERS FOR YOUNG ASTRONOMERS. 



By Frank 0. Dennett. 

 {Continued from page 215.) 



Minor Planets. 



Between the orbits of Mars and Jupiter lie the 

 paths of an immense number of tiny planets, of 

 which nearly five hundred have been discovered. 

 The first, Ceres, was first seen by Piazzi at Palermo 

 on January 1st, 1800, and three others were found 

 —Pallas in 1802, Juno in 1804, and Vesta in 1807. 

 Juno was discovered by Harding of Lilienthal with 

 a very poor telescope of 2 inches aperture, and 

 Vesta by Olbers with an ordinary night glass. 

 The brightest of these, Vesta, never exceeds the 

 6th magnitude. At this time real hard work was 

 necessary to find a planet ; first star maps had to 

 be constructed showing all stars down to about the 

 9th magnitude. These maps had to be continually 



time photography has almost entirely replaced 

 visual searching for these little bodies. The photo- 

 graphs by Professor Max Wolf, taken with the 

 16-inch Bruce telescope on November 4th, 1901, 

 and with the 6-inch portrait lens on March 21st, 

 1892, the former enlarged three and a half and the 

 latter six times will show what these trails are 

 like. In each case the plates were exposed 

 for two hours. It was stated in the "Bulletin 

 Astronomique " for October 1896 that, out of thirty- 

 nine plates exposed, eleven showed no planets, 

 whilst the rest contained the trails of no less than 

 fifty-two planets — forty-six old, and six new dis- 

 coveries. Sometimes several new ones have been 

 observed on one plate, as, for instance, on 

 October 31st, 1899, when three were so found, and 

 on one occasion there were no less than five. 



The orbits of these tiny worlds are often so 

 inclined from the plane of the ecliptic that they 

 are sometimes known as ultra-zodiacal planets. 



