Manchester Memoirs, Vol. I. (1906), No. 1. 5 



observations for position, with the efficient aid of the Royal 

 Engineers, and last year, one of the prominent members 

 of this Society, Mr. Stromeyer, made some ingenious 

 suggestions for work of this kind at the eclipse which was 

 to take place on August 30th. He had in view not only 

 the determination of places of the sun and moon, but the 

 measurement of distances on the earth's surface, if the 

 observations could be made at more than one place. I 

 had the pleasure of discussing the possibilities with him, 

 and at one time I hoped that something might be done at 

 any rate to make the preliminary trial of his ideas, which 

 might encourage more complete application of them in the 

 future. But when the time arrived, and the difficulties of 

 work in Egypt were fully realised, it became clear that 

 any such attempt must be dropped unless we could afford 

 to sacrifice observations demanded by considerations of 

 continuity. 



Total eclipses have, however, one great disadvantage — 

 their extreme rarity. The spot on the earth from which 

 the sun is entirely obscured from the moon is a very small 

 one. If we cover up the sun's disc with, say, a threepenny 

 bit held at arm's length, we can only cover it up for one eye ; 

 if we open the other eye the sun is not obscured from it, 

 as we become painfully aware. And so though one spot 

 on the earth may be favoured by a total eclipse, another 

 at a little distance is not. The favoured spot does not 

 remain stationary on the earth owing to the motion of the 

 moon between us and the sun, and also to the rotation of 

 the earth. It travels over the surface ; but even so the 

 track made is narrow compared with the wide area over 

 which the partial eclipse is visible. Moreover the track 

 has a wayward habit of wandering across regions which 

 are either inaccessible or occupied entirely by ocean ; and 

 although we could in the latter case enjoy the spectacle 



