June 14, 1888] 



NATURE 



'53 



to the existence of the downward current in cyclones, 

 it renders M. Faye perfectly helpless when he con- 

 templates an anticyclone. In the presence of such a 

 formidable foe he is completely disarmed. Here, just 

 where a downward current would come in really useful, 

 he finds he has used it all up. All he can say, there- 

 fore, is that they have nothing cyclonic about them, 

 which is quite true. 



M. Faye concludes by drawing up a list of questions 

 which relate to the phenomena exhibited by cyclones, 

 tornadoes, and waterspouts, and which he considers yet 

 unsolved. Some, doubtless, still await a more complete 

 explanation, but we think the list might be considerably 

 curtailed if M. Faye would descend, if possible, in one of 

 his favourite eddies, and meet the aspiring meteorologist 

 half-way. Atmospheric phenomena seldom present them- 

 selves in the form of purely mechanical problems. If, as 

 M. Faye says, the question " is not one which can be 

 treated by actual methods of rational mechanics on 

 which everyone can agree," we are equally confident 

 that it is one whose solution cannot be attempted without 

 the aid of rational physics, or without reference to the 

 facts already established by observation. 



E. Douglas Archibald. 



THE 



VISITATION OF THE ROYAL 

 OBSERVATORY. 



T'HE Report of the Astronomer- Royal to the Board of 

 -*• Visitors of the Royal Observatory was read at the 



annual visitation on June 2. 



One of the first points touched on in the Report is the 

 threatened railway invasion of the Observatory. 



The subject of approaching railways has again, after a lapse 

 of many years, engaged our serious attention. Early in March 

 notice was received from the Home Office of a proposal to 

 carry a railway (in extension of the authorized Bexley Heath 

 Railway) in a tunnel across Blackheath, the nearest point being 

 840 yards from the Observatory. As there was reason to believe 

 that this railway might injuriously affect the Observatory, pre- 

 liminary observations of the effect produced by trains on the 

 existing Greenwich and Maze Hill Railway were at once com- 

 menced, the observations being made on six nights with the 

 transit-circle, and the disturbance in the image of the wires, as 

 seen by reflection from the trough of mercury, being noted. It 

 resulted from these experiments that trains on this railway caused 

 great disturbance during their passage, not only on the section 

 between Greenwich and Maze Hill, the nearest point of which 

 is 570 yards from the transit-circle, but also on the line beyond 

 Greenwich on the London side and beyond Maze Hill on the 

 Woolwich side. The distances of the Greenwich and Maze Hill 

 stations from the Observatory are about 970 and 670 yards re- 

 spectively. There was also evidence of disturbance caused 

 presumably by trains on the Lewisham, Blackheath, and 

 Charlton line, at a distance of about a mile from the Observa- 

 tory, but we could only infer the times of passage of these trains 

 from the published time-tables. 



In order to establish conclusively the connection between 

 definite disturbances and trains, arrangements were made to note 

 the times of arrival and departure of trains on the Greenwich 

 line and at Blackheath, facilities for doing this having been 

 courteously given by Mr. Myles Fenton, the Manager of the 

 South-Eastern Railway. Observations were made on this plan 

 on five nights, one observer being stationed at the transit- circle 

 to record all disturl ances of the reflected image, while another 

 observer travelling up and down the Greenwich line, and a third 

 observer at Blackheath, noted the times of arrival at and 

 departure from the stations. It was found that the disturbance 

 was very great during the passage of trains between Greenwich 

 and Maze Hill, the reflected image being invisible while the 

 train was in the tunnel, at a minimum distance of 570 yards, 

 and that there was considerable disturbance during the pa-sage 

 of trains through the Blackheath-Charlton tunnel, at a distance 

 of a mile, the reflected image becoming occasionally in- 

 visible. As the tunnel of the proposed railway would be 



similar in character to this, but at half the distance, it was con- 

 cluded that it would cause so great a disturbance as to make 

 delicate observations impossible. On my notifying this to the 

 Admiralty, the Bill was opposed on the part of the Government, 

 and as a consequence of this the clauses authorizing the con- 

 struction of the railway across Blackheath were abandoned. 



I may here mention that the extension of the London, Chat- 

 ham, and Dover Railway from Blackheath Hill to Greenwich, 

 which was authorized in 1 881, is now in course of construction. 

 I hope that, though the terminus of this line is distant only 620 

 yards from the Observatory, the tremor fr im trains will not have 

 sufficient time to produce the full accumulated effect in the short 

 interval between Blackheath Hill station and the terminus. But 

 if at any future time a further extension of this line should be 

 proposed, the question would require very careful consideration 

 in the interests of the Royal Observatory. 



The following statement shows the number of observa- 

 tions made with the transit-circle in the period of 356 days 

 ending May 10, 1888 : — 



Transits, the separate limbs being counted as separate 



observations ... ... ... ... ... ... 5304 



Determinations of collimation error .... ... ... 294 



Determinations of level error ... ... ... ... 351 



Circle observations ... ... ... ... ... ... 5067 



Determinations of nadir point (included in the number of 



circle observations) ... ... ... ... ... 331 



Reflection-observations of stars (similarly included) ... 503 



About 350 transits (included in the above number) have been 

 observed with the reversion-prism, to determine personality 

 depending on the direction of motion. 



The very bad weather in the first four months of this year has 

 seriously affected the number of observations with the transit- 

 circle. 



The total number of observations made with the 

 altazimuth is as follows, the observations having been as 

 usual restricted to the first and last quarters in each 

 lunation, except during the winter, when, in the absence 

 of suitable objects for equatorial observations, the moon 

 was observed throughout the lunation. 



Azimuths of the moon and stars 354 



Azimuths of the azimuth mark 114 



Azimuths of the collimating mark 116 



Zenith distances of the moon and stars 209 



Zenith distances of the collimating mark 116 



In consequence of the building operations for the extension of 

 the computing-rooms the collimating mark was dismounted on 

 November 9, and the view of the azimuth mark has been 

 obstructed by the new building from the beginning of December. 

 Since then the collimation and azimuth errors have been deter- 

 mined entirely by observations of high and low stars. It is 

 proposed, when the work on the new building is completed, 

 to select two azimuth marks, one distant and the other 

 sufficiently near to be seen in the foggy weather of the winter 

 months. For distinct vision of the latter a lens of very long 

 focus would be required, and it would thus be available strictly 

 as a collimating mark. 



All will regret to hear that no progress has been made 

 since the date of the last Report in the construction of the 

 new 28-inch refractor, owing to difficulty in obtaining the 

 crown disk. The flint disk made by Messrs. Chance 

 seems to be satisfactory, but up to the present neither that 

 firm nor M. Feil's successor has succeeded in making a 

 crown disk. 



Attempts have been made to show if anything is gained 

 in sidereal photography by using curved plates. For 

 this purpose a 4-inch photographic object-glass by Dall- 

 meyer, belonging to one of the photoheliographs, was 

 mounted at the end of June in a light wooden tube, and 

 firmly attached to the side of the telescope tube and 

 parallel to it, to carry out experiments on the extent of 

 field available on plane and curved plates respectively, 

 the latter being moulded by Messrs. Chance to a radius 

 of 22 inches, corresponding to the curvature of the field, 

 if the circle of least confusion be taken for the image. 

 We read : — 



