4 Turner, To fa/ So/ar Ec/z/>ses. 



to suppose that the planet Mercury, which is nearer the 

 sun and therefore moves more rapidly, would be affected 

 at least as much as the earth. Mr. Cowell has accordingly 

 tested* this hypothesis by analysing the observations of 

 transits of Mercury, and found confirmation of the change 

 in the earth's motion, but no evidence of change in that of 

 Mercury. We have learnt, however, in Astronomy to be 

 patient in expecting the interpretation of results so long 

 as we can make sure of their reality from observation,, 

 and we may await therefore with patience, although with 

 great interest, the unravelling of this new puzzle which 

 Mr. Cowell's preliminary work has introduced to us. 



For the present it is enough to remark that although 

 this work lies in a region where partial eclipses are not 

 by any means useless, nevertheless even here the 

 superiority of total eclipses is manifest. It is one of the 

 points made by Mr. Cowell that the records are much 

 safer to interpret when there is some reference to the 

 appearance of the Corona, and we are able to infer that 

 the eclipse was total. In modern times, also, observations 

 of position are certainly rendered more complete on the 

 occasions of total eclipses, although it is not often that 

 advantage can be taken of this fact, chiefly on account of 

 the more pressing need for spectroscopic and other ob- 

 servations on the nature of the Corona. In 1887, however, 

 the late Otto Struve organised an extensive programme of 

 observations of this kind, hoping to measure very exactly 

 not only the relative places but the relative sizes of the 

 sun and moon. Unfortunately, cloudy weather prevented 

 observations of that eclipse, and not only Struve's assistants 

 but some forty other European Astronomers from all 

 nations returned home disappointed. In 1898 the 

 Astronomer Royal carried out in India a programme of 



* Jl/ivi. Not. Roy. Astron. Sjc, vol. 66, p. 36. 



