VOL. IX.] PHILOSOPHICAL TRANSACTIONS. 131 



organographia of my machina coslestis. But although Mr. Hook, and Mr. 

 Flamsteed, and others, be of a different opinion, yet I have been, and still am 

 taught by daily experience, that the matter is far otherwise in those large in- 

 struments, as quadrants, sextants, and octants, especially in azimuth quadrants, 

 and other quadrants constructed of rulers or bars, which cannot so easily, or in- 

 deed by any means, be disturbed and inverted (while examining dioptric teles- 

 copes) as those instruments of 3 or 4 feet constructed with a perpendicular. 

 The matter chiefly consists in this^ that they can undertake no observation with 

 their telescopic sights, till they examine and rectify them anew; in which 

 examination there are various ways, and much room for mistake, however care- 

 fully it may be done. And indeed I cannot understand how this examination 

 can be performed, in azimuthal quadrants, octants and sextants, at all times, 

 with convenience, and without much loss of time. 



There are some also I see, among whom is Mr. Flamsteed, who have under- 

 taken to give judgment on my observations, whatever they may be, before they 

 have examined or seen them. I am not given to a vain boasting of my own affairs, 

 nor did ever imagine, that in this attempt at the restitution of the fixed stars, 

 knowing my own weakness, that I should be perfect in every thing. But this I 

 am convinced of, that if I had undertaken the business by means of telescopic 

 sights, I must not only have wasted many years in fruitless examinations, but I 

 should doubtless have been disappointed of my hopes, and that on various ac- 

 counts, not necessary here to mention. Hence I congratulate with myself, that 

 I never could adopt that opinion, but that whatever by God's help I have per- 

 formed, it has been done after my own manner : but when w^e shall have ob- 

 servations made in both ways, continued for a series of 20 or 30 years, that is, 

 as well those that may be made with telescopic sights, as those derived from the 

 heavens by our plain sights ; the matter will then be brought to a fair trial. In 



Kepler was doubtless a genius of the first rank, and possessed a pure and rigid mathematical taste. 

 He made some splendid discoveries 5 particularly the true laws of the planetary motions j viz. tliat 

 they move in ellipses about the sun, describing equal areas in equal timesj and that their periods and 

 distances are all regulated by one general law, the squares of the former being always proportional to 

 the cubes of the latter : laws however which he discovered, not a priori, by philosophical reasonings, 

 but by tracing out and comparing their motions as recorded in tlie observations of Tycho : it being 

 reserved for the immortal Newton to demonstrate the truth and indispensable condition of those laws. 

 Kepler had some idea of the sun's restraining influence over the planets, which he judged to be an 

 attraction of a magnetical nature. He was addicted to judicial astrology, and sometimes even fancied 

 that the earth and sun were animated beings. Kepler's writings and works were very voluminous, and 

 some of them very learned. Among them, is one on the gauging of wine casks, said to have au 

 origin whimsical enough, being occasioned by a quarrel he had with an excise officer, whom he ac- 

 cused of an erroneous estimate in gauging the wine vessels used on occasion of his wedding dinner. 



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