430 Observations on the Us€ 



But with regard to the Sun, things are different : his Right 

 Ascension is given for every day in the year ; accordingly we 

 find his Transit regularlj/ taken, whilst those of Dr. Maske- 

 lyne's catalogue, of iiifinitely greater importance, are very ge- 

 nerally neglected. 



This allusion to the Sun brings me to the mention of a cir- 

 cumstance, not I believe generally known ; namely, that the 

 Error of the Clock, as shewn by his Transit, is not unfrequently 

 very far from the Truth: indeed it is a Fact, upon which 

 reliance may be placed, that whilst the Errors of the Clock, 

 as deduced from several ♦S'lrferea^ Transits, shall not differ from 

 each other above two or three hundredths of a Second, the Sun's 

 Transit will give one varying three or four Tenths ; and that, 

 too, where the Instruments employed, are of the larger sort, and 

 where everj/ Precaution is constantly taken, to prevent the 

 Sun's Rays from deranging the position of the instrument. 



Now, if such be the case, where large Instruments are used, 

 surelj/ where small ones are employed, greater Errors may be 

 expected; for [these are liable, to all the Errors of large In- 

 struments, as well as those which their diminutive Form, and 

 Metallic vSupports, are, from exposure to the Sun's Rays, sure 

 to entail upon them. 



Hence, therefore, the impropriety of depending upon the Sun's 

 Transit, to correct the Error of the Clock, and the absolute 

 necessity of recurring to those of the Stars, for Accuracy of 

 Time, not less than Accuracy of Position. 



If, then, what I have hinted at, is the principal cause of 

 error, the Remedy is obvious : let no inducement be held out to 

 Observations of the Sun, which is not afforded to those of the 

 Stars ; and then, and not till then, will the observations made in 

 private Observatories be generally worth recording. 



Under this persuasion it is, that I beg to offer to the public, 

 the accompanying Corrections in Right Ascension of the 

 Thirty-six Principal Fixed Stars, to every day of the pre- 

 sent Year ; they are computed from the Tables of Dr. Maske- 

 lyne's, before alluded to, and will be found, I believe, tolerably 



