Observations y and Harriots MSS. 317 
serve the spots on the 8th of December in 1610, and that he 
continued to observe them, at irregular intervals, to the 18th of 
January 1613. The observations recorded are 199 in number, 
and the accounts of them are accompanied with rough drawings, 
representing the number, position, and magnitude of the spots. 
From the manner, however, in which these observations appear 
to have been made, and also from that in which I find them re- 
corded, I do not think that Harriot ever intended them for pub- 
lication ; nor do I think that the publication of them now would 
either satisfy rational curiosity, or contribute in the smallest de- 
gree to the advancement of astronomy. The circumstances un- 
der which the observations were made are very briefly and very 
vaguely recorded, and consequently no calculations can be found- 
ed upon them likely to lead to accurate conclusions. These de- 
ficiencies I am inclined to attribute, partly to his having had no 
intention to publish on the subject, and partly to the imperfec- 
tion of astronomical and philosophical instruments in his time. 
From this class of papers of which I am now speaking, it 
plainly appears, that Harriot had no coloured glass to defend 
the eye, for the following expressions frequently occur : A 
mist,” — a notable mist,” — “ misty and cloudy,”— the sonne 
was somewhat to cleare. There^being no cloudes but only thick 
ayer,”—- convenient thin cloudes,” &c. 
As there is no reason to doubt of his diligence, I think that 
such expressions as the following are to be attributed to the im- 
perfections of his instruments, and not to his want of care : The 
altitude of the sonne being 7 or 8 degrees,” — the sonne being 
3 or 4 degrees hy,” &c. 
The next class of papers (fixed together with a pin) which met 
my eye, is entitled, “ Descriptio parabolae per circularum motum.” 
This I proceeded to examine, with sanguine hopes of finding a 
practical method of describing a parabola by an uninterrupted 
motion. My hopes, however, quickly vanished ; for this class 
only contains diagrams so rough and confused, that it does not 
appear from them, upon what property of the circle he founded 
his attempt. < 
After this disappointment, I proceeded to examine a class of 
papers entitled De Jovialibus Planetis.” From two pages of 
these papers, it appears, that he first observed Jupiter’s Sate}- 
