796 



NA TURE 



[June 17, 1922 



conducted at the Welsh plant-breeding station are 

 primarily intended to be of service to agriculturists 

 in Wales, and are therefore bound to be of equal 

 value to farmers generally in elevated areas in regions 

 of high rainfall. 



The chief aim of the station is to investigate 

 problems connected with herbage plants with the view 

 of producing improved strains of such important 

 plants as red clover, lucerne, the rye grasses, cocks- 

 foot, and all other grasses suitable for inclusion in 

 mixtures for temporary and long-duration pastures. 

 Researches on these lines are now well advanced, 

 interesting reports having been issued from the station 

 on the work so far conducted. The oat crop is also re- 



ceiving detailed attention ; the possibility of extending 

 the practice of growing winter oats is being explored, 

 and endeavour is being made to produce hardier, 

 earlier, and stiffer-strawed varieties suitable to Welsh 

 conditions. It should be stated that the potato, barley, 

 and root crops are not being studied at the station. 



Welsh agriculturists must not expect to see the full 

 benefits from Sir Laurence Philipps's foresight and 

 the developments that have followed from the 

 foundation of the station until after the lapse of a 

 number of years — for plant-breeding is a slow and 

 laborious business based on the gradual building up 

 of strains each of which can only be. the outcome of 

 prolonged investigation. 



The Royal Observatory, Greenwich. 



THE report of the Astronomer Royal presented at 

 the annual visitation of the Royal Observatory, 

 Greenwich, on J une 3 , deals with the year ended on May 

 10. The observations for the seven-year star catalogue, 

 1915-1921, have been concluded, practically all the 

 stars having been observed at least seven times ; they 

 include all stars in the Backlund-Hough list north 

 of declination - 28°. The determination of their proper 

 motions is now in progress. The working catalogue 

 in use since January last includes all the stars brighter 

 than the eighth magnitude (with some fainter ones 

 in sparse regions) between North Decl. 32° and 

 64°. It will be remembered that the zones from 

 N. 24° to N. 32° and from N. 64° to N. go° were 

 covered in recent Greenwich catalogues. The epoch 

 1925 is adopted for all catalogues about the present 

 time, in accordance with a resolution of the Astro- 

 nomical Union. 



A change has been made in the method of deter- 

 mining azimuth error of the transit-circle. Formerly 

 it depended upon observations of the nine standard 

 polars within 3^° of the pole ; a list has now been 

 made of 70 stars the polar distances of which lie be- 

 tween 13° and 45°, most of them bright enough to be 

 observed in daylight ; as many of these as practicable 

 are observed daily at both culminations, using the 

 travelling-wire micrometer, thus greatly reducing 

 the personality that was present in the previous 

 method of hand-tapping used for the close polars. 

 The latter stars will still be observed for place ; 

 their positions will no longer depend solely on double 

 transits of Polaris, which were only obtainable for 

 restricted periods of the year. The clock-star list 

 has been modified by removing two very low stars 

 and inserting eleven new ones to fill gaps. 



The moon was observed on 126 nights ; the average 

 correction required to the Nautical Almanac value 

 of the longitude is 13-38". After the end of 1922 

 Brown's tables will be used in the Almanac, and there 

 will be a discontinuity in the errors. 



Eighteen consecutive divisions of the transit circle, 

 covering an arc of i4°, have been obliterated from 

 some unknown cause in recent years ; new divisions 

 have recently been cut with a small steel scriber 

 that was screwed to the bracket holding the pointer. 

 The new divisions are very sharp, and the errors of 

 graduation are very small. 



The distribution of temperature in the neighbour- 

 hood of the instrument has been studied ; ther- 

 mometers are now read outside both the north and 

 the south walls of the observing room ; they fre- 

 quently show differences of some degrees, depending 

 apparently on the direction of the wind ; it is there- 

 fore somewhat difficult to know what temperature 

 should be employed when computing refraction. 



The recently published volumes dealing with the 

 results of the observations made with the Cookson 



NO. 2746, VOL. 109] 



floating telescope between 191 1 and 1918, and with 

 the observations and orbits of the double stars observed 

 with the 28-inch refractor since 1892, have already 

 been noticed in Nature. The latter observations are 

 being continued, 253 pairs having been measured dur- 

 ing the year, of which 56 had separations less than 0-5". 



The Thompson equatorial has been used, as before, 

 for the photographic determination of stellar paral- 

 laxes. In all, 896 plates have been measured during the 

 year, and the parallaxes of 48 stars deduced, with a 

 mean probable error of 0-009"; altogether 142 paral- 

 laxes have now been determined with this instrument. 



The 30-inch reflector has been used for a photo- 

 graphic determination of the wave-lengths of 

 maximum photographic intensity in stars of different 

 colours. A grating of steel wire, i -42 mm. in diameter, 

 was used to produce diffraction images, the effective 

 wave-length being found from the separation of 

 images ; the results, which were communicated to the 

 Royal Astronomical Society, indicate that the graph 

 connecting wave-length with spectral type is dis- 

 tinctly non-linear. An extension of this work, 

 suggested by Prof. T. R. Merton, is now being com- 

 menced. A 7-inch prism has been borrowed from the 

 joint permanent Eclipse Committee ; this will be 

 mounted in front of the 6-inch Franklin-Adams lens, 

 for which an aluminium camera has been made 

 coarse wire-grating will be placed in front of the prism. 



The astrographic equatorial was used to complete — 

 the magnitude determination of stars in the Harvard 

 polar sequence. The results, which are in good 

 accord with those obtained at Mt. Wilson, were 

 published in the Mon. Not. R.A.S. of last November. 

 The instrument has now been taken to Christmas 

 Island for the eclipse of next September. The latest 

 report stated that the mounting had been set up, 

 except part of the driving clock. It has been arranged' 

 to take photographs of the Kapteyn areas in zones: 

 15° N., 15° S., and 30° S. in order to connect the 

 northern and southern magnitude scales. 



Sunspot activity declined considerably during thei 

 year ; there were, however, some prominent groups, 

 of which the largest two crossed the central meridiaa 

 on 1921, May 14, and 1922, March 2. 



The mean values of the magnetic elements for 192 1' 

 and the three previous years were as follows : 



Denotes that these values are provisional. 



