On the late Solar Eclipse. 44 1 



I think they owe it to the public to reconcile this singular dif- 

 ference between them. 



The same remark will apply to two other observers in the 

 town of Ipswich, viz. Mr. Capel LofFt, and Mr. Acton, as in- 

 serted in the same Magazine to which I have just referred. 

 Here we find a difference of no less than one minute and n 

 quarter in the time of the ending of this eclipse, although they 

 both agree as to the time of the commencement. This dif- 

 ference appears to be there attributed to the superior power of 

 one of the telescopes: a very improbable and a very absurd so- 

 lution of the difficulty. For, independent of the impossibilitv 

 of any telescope (however powerful) making so wonderful a dif- 

 ference in the.ending of this eclipse, it ought to have caused a 

 similar difference in the time of the commencement. Indeed we 

 sometimes find that there does exist a slight difference in the 

 observed time of the commencement of an eclipse, but seldom 

 any difference in the time of the ending of it: because in the 

 former case, one observer may catch the first impression of the 

 moon on the sun's disc before the other ; but, in the latter case, 

 they can i)oth follow the moon's course to the very edge of the 

 sun's disc with ecjual facility and correctness, and thereby tell 

 exactly the time at which the reparation of the two bodies takes 

 place. 



Before I dose this letter, I cannot help adverting to Mr. 

 Groombridge's explanation of the error in the Nautical Alma- 

 nac, which had been noticed in one of your former numbers, 

 relative to the point where the moon makes the first impression 

 on the sun's disc, in this eclipse. He s^'s that the number of 

 degrees is right if applied to the moon's vertex as it relates to 

 the plum of the equator, and that it ought to have been so 

 expressed But surely it cannot be necessary to inform Mr. 

 Groombridge that in o// cases of this kind, the angle is reckoned 

 from the vertex as referring to the plane of the horizon only; 

 and that the very design of noticing it in the Nautical Almanac, 

 was to enable an observer to point his telescope to that part of 

 the sun's disc : which could not be done if the vertex related to 

 the plane of the ecliptic or of the equator. In fact, Mr. Groom- 

 bridge catmot produce any Nautical Almanac, ever since the 

 first publication of that work, wherein any other interpretation 

 of the phrase is intended : neither do I think that he can men- 

 tion any treatise on the science, wherein any other-mode is given, 

 for determining the point where the moon first touches the sun's 

 disc, than that which measures the angle from the vertex as it 

 relates to the ptune of the horizon. 



One word more on the subject of this eclipse. Mr. Groom- 

 bridge observes that it was total in the northern parts of Russia, 



on 



