220 Mr. South on the Eclipses of [March, 



deem made under the most favourable circumstances, cannot be 

 read without making a deep impression on the mind of the 

 reader. We must, however, remember, that these sentiments 

 were founded upon comparison of all the observations of eclipses, 

 which had been made from the year 1662 to the year 1802 ; and 

 there will be little difficulty in believing that the chaotic mass 

 would fully justify the assertion ; for among the earlier obser- 

 vations immense discordancies would naturally be found ; but I 

 feel little hesitation in saying, that the observations which have 

 been made since the year 1802 would be far more than sufficient 

 to entitle the accuracy of the assertions, as far as they relate to 

 modern observations, not only to be disputed, but even to be 

 disproved. Observations made during 100 years at Greenwich 

 and Paris, did not determine the difference of the two meridians 

 nearer than 10 seconds. But observations made during seven 

 months in Blackman-street and at Bushey, gave the difference of 

 longitude to 17 hundredths of a second. 



2. In a table which will be given presently, there are three 

 observations of the third satellite, each coming far within two or 

 three minutes of the truth ; we shall also produce observations 

 of eclipses of the fourth, liable to infinitely less error; hence 

 I cannot coincide with our author, in the justice of his remarks. 



3. From the recorded observations of immersions and emer- 

 sions of the- fourth satellite, it is evident enough that the incon- 

 gruities are considerable ; and if examined, as our own will 

 hereafter be, they are found irreconcilable ; hence supposing the 

 same observers, the same instruments, and the same weather, 

 at each station, both at the immersion and emersion, we may 

 safely infer, that the telescopes were long and unmanageable ;* 

 and consequently would afford results inconsistent not only with 

 each other, but with themselves. 



4. As to the immense discordancies between the observations 

 of the same eclipse related in the last paragraph ; they do indeed 

 place the observers and their instruments in the back ground ; 

 for it would be difficult to account why the observed periods of 

 immersion or emersion should differ more than the time which 

 the satellite requires to travel through a portion of space, equal 

 to its own diameter. 



On consideration of these passages then, I am induced to 

 apply the sentiments they convey, more to the earlier observa- 

 tions, than to those of modern date ; still there can be no doubt 

 but that an immense quantity of the latter will be necessary, to 

 invalidate the monstrous inaccuracies of the former. An obser- 

 ver, however, of the present day, will, 1 think, let his respect for 

 the name of Delambre be great as it may, have some difficulty 

 in supposing, that similar incongruities would attend observa- 

 tions of similar phenomena, now that telescopes are better made, 

 and what is almost of as much importance, better mounted. 



• When it is known that they were from 1 5 to 20 feet in focal length, there will be 

 some difficulty in arriving at any other conclusion. 



