340 Life of the Rev. John Flamsteed, [Nov, 



works. In the mean time whoever will but read what he 

 hath written (page 733, the third problem) will find how 

 groundlessly he introduceth it, if they but seriously consider 

 that the difference of the parallax of the moon's centre and 

 her superior horn is equal to the difference of the parallax 

 of her centre and her inferior horn; with a very small 

 difference which will scarce ever arise to half a second were 

 her diameter double the breadth it is. 



Some considerations, likewise, of the different equations 

 of time used by several astronomers, though well demon- 

 strated by none, caused me to strive for a demonstrable 

 equation. I studied hard in this, and at first was of opinion 

 that the natural days were always equal, and that there 

 needed no equation of time. Whilst striving to demonstrate 

 this I proved the contrary : first that the excentricity of the 

 earth's orbit from the sun's centre caused an inequality ; 

 and afterwards that the ecliptic's obliquity caused another 

 inequality of the apparent day, which two causes applied 

 together would make the absolute equation of time. But 

 because I have elsewhere said enough of this already in a 

 letter of three sheets to Mr. Halton, I shall say no more of 

 it in this place. I likewise endeavoured something in the 

 obliquity of the ecliptic ; the sun's true distance from the 

 earth, and the mean length of the tropical year; in all 

 which I have laboured with much difficulty this last April. 

 And now I have brought my sheets up to my age, and have 

 finished this the 8th day of May 1667. Deo gloria. 



[Here this portion of the M.S. terminates. But Flam- 

 steed has added a kind of postscript thereto, which being 

 short, the Editor transcribes.] 



Afterwards I followed my mathematical studies closer, 

 but kept no special account of my proficiency. I met with 

 new authors, read something of Euclid and employed myself 

 in several readings till the latter end of the year 1669, when 

 I wrote an Almanac for the following year, not after the 

 usual manner but much more accurately; inserting an 

 eclipse of the sun that might have been observable, but was 

 omitted in the Ephemerides, and five appulses of the moon 

 to fixed stars. 



But this being rejected as beyond the capacity of the 

 vulgar, and returned to me, I excerpted the eclipse and 



