SCIENCE- G OS SIP. 



59 



friends have been blaming one or two of the 

 opticians. Jupiter will not need such high powers. 

 Besides appropriate magnifying powers, moments 

 of best definition have often to be waited for at 

 the expense of nmch patience. 



The Greenwich Visitation.— Saturday after- 

 noon, June 1st, 1901, proved dull so far as the 

 weather was concerned ; but a fair number of 

 visitors were present at the Royal Observatory on 

 the occasion of the annual " Visitation " by the 

 President of the Royal Society (Sir W. Huggins) 

 and some sixteen other official visitors to receive 

 the Astronomer Royal's report. The report con- 

 cerns the year ending May 10th, 1901. Some of 

 its details show that the proposed extension of the 

 space around the observatory and the improved 

 fire-extinguishing arrangements have not yet been 

 carried out, but that the electric light installation 

 has been extended since October last to the library 

 rooms in the basement of the new observatory. 

 A " Rapid Rectilinear " lens of 4 inches aperture 

 and 33 inches focus has been obtained for stellar 

 photography and for use in eclipse observations. 

 The transit circle has been fully occupied during 

 the year, no less than 10,938 transits of heavenly 

 bodies being observed, and 9,838 circle observa- 

 tions made, besides a number for the determina- 

 tion of errors, the actual list of stars observed 

 containing 4,787. The transits and circle observa- 

 tions have been completely reduced so far as the 

 end of 1900, and those up to the middle of April 

 partially so. The second ten-year catalogue of 

 6,892 stars for 1890 has been printed and is being 

 distributed. The preparation of this catalogue 

 necessitated the reobservation of all the stars in 

 Groombridge's Circumpolar Catalogue (1810) as 

 well as of fundamental stars. The new altazimuth 

 instrument with its chronograph, also new, has 

 been working satisfactorily all the year, except 

 that in October the spring of the telescope micro- 

 meter had to be replaced, having proved to be too 

 weak. With the equatorial telescopes eighteen 

 disappearances and ten reappearances of stars 

 occulted by the moon have been observed. The 

 28-inch refractor has been employed in mea- 

 suring 346 double stars, 105 of which were 

 less than 0" - 5 apart. As a rule, stars separated 

 by less than l"-0 have been measured on three 

 nights each, and wider pairs on two nights. 

 Amongst other pairs measured are Capella, k Pegasi, 

 and 3 1266, whose distances do not exceed 0" - l. 

 On April 30th the position micrometer belonging 

 to this instrument was injured by accidentally 

 striking the floor, which the telescope does not 

 clear when pointing near the zenith, its quarters 

 being really too small. During the repair the 

 micrometer of the Sheepshanks telescoiDe was fitted 

 to the large instrument. With the 26-in. Thompson 

 achromatic 255 photographs were taken to aid in 

 the endeavour to obtain the solar parallax by 

 observation of the planet Eros during the recent 

 opposition. Besides these, 24 photographs were 

 likewise obtained of Comet i, 1900. With the 

 astrographic equatorial telescope 294 photographs 

 were taken of Eros, 139 of Nova Persei, and 3 of 

 Comet b, 1900, besides 164 for the great chart and 

 73 for the catalogue ; in all 682 plates were ex- 

 posed. Good progress has been made with measur- 

 ing the plates, so that two-thirds of the total work 

 of measurement undertaken by Greenwich has been 

 accomplished. Where the new measures record 

 111,754 stars, the " Bonn Durchmusterung " only 



shows 15,865 stars. The new star in Perseus was 

 successfully photographed 136 times on forty nights, 

 but unfortunately the film on the 30-inch reflector 

 was so tarnished that it was found impossible to 

 obtain a photograph of its spectrum. It has been 

 resilvered, and since March 28th a number of 

 successful photographs of stellar spectra have 

 been taken, some of which were shown, and proved 

 very interesting, the varying displacement of the 

 lines in spectroscopic doubles being well shown 

 on some plates. Photographs of the Sun to the 

 number of 334 were taken on 167 days. The 

 magnetic observations have been regularly taken. 

 The principal results for 1900 are : Declination, 

 16° 25'-0 west; horizontal force, 4-0014 in British 

 or 1-8450 in metric units ; dip, 67° 8' 27". 

 The observations have been made in the new 

 Magnetic Pavilion. There have been no great 

 magnetic disturbances during 1900, and only eight 

 lesser disturbances. The mean temperature of the 

 year 1900 was found to be 50 o, 5, or l°-0 above the 

 average of the fifty years 1841-90. On July 16th 

 the highest shade temperature in July was reached 

 since 1881, and only once beside during the past 

 sixty years, in 1868, has it been exceeded, and 

 once, 1876, equalled. The greatest cold of the 

 year was on February 14th ; then ll°-6 Fahr. of 

 frost was registered. During the twelve months 

 ending April 30th 1,513 hours of bright sunshine 

 were registered out of a possible 4,457 hours. 

 During the same year the rainfall was 4 - 32 inches 

 short of the average of fifty years. The rainfall 

 has been below the average every year since 1894. 

 The usual work of testing chronometers and deck- 

 watches was carried on, the total number received 

 being 1,118. Arrangements are being made to 

 redetermine the Greenwich-Paris longitude in 

 October next and the following spring in conjunc- 

 tion with the French observers. The reports of 

 the eclipse expedition to Spain in May 1900 are 

 now public property, and so need not be further 

 mentioned here. The present report finds Mr. 

 Dyson at Sumatra, and Mr. Maunder at Mauritius, 

 to observe the Solar eclipse of May 18th. The 

 concluding paragraph of the report says : — 

 "Within the last five months one-third of the 

 whole staff of computers have left the observatory 

 for other posts, and have had to be replaced by 

 boys new to their work. Such an extensive change 

 in the temporary staff has, to a certain extent, dis- 

 organised the work, and has thrown a great strain 

 on the assistants who are charged with carrying 

 it on under such difficult conditions. Considering 

 the training and experience required in the varied 

 work which at Greenwich has to be done by com- 

 puters, a greater degree of permanence in the staff 

 appears to be necessary for the continued efficiency 

 of the observatory." A just request very mode- 

 rately put, but still an urgent necessity. — F. C. 

 Dennett. 



CHAPTERS FOR YOUNG ASTRONOMERS. 



By Prank C. Dennett. 



(Continued from p. 21.) 



SATURN'S SYSTEM. 



Undoubtedly the most beautiful member of our 

 system is Saturn, with his rings and moons. The 

 smaller telescopes show him to be magnificent, whilst 

 every increase of aperture exhibits greater beauty, 

 and the largest instruments are still taxed to show all 



