of the earliest Trigonometrical Canon. 525 



taught at Paris, but was prevented by being obliged to learn 

 and practise medicine in the stead of a certain patron, Mccce- 

 natis cujusdam loco. What this means I do not know : per- 

 haps loco is a misprint for domo. I'hough Otho does not 

 mention that Rheticus practised medicine, he to a certain ex- 

 tent confirms Ramus, by stating that his friend died at Cassau, 

 in Hungary, on his way home, after being called out by a 

 certain baron. I mention these things, because it is never 

 stated that Rheticus was a physician. He died in 1576, in 

 the sixty-first year of his age. 



With regard to the choice of intervals of ten minutes, it may 

 have been dictated by the existing state of astronomy ; but it 

 is more than likely that Copernicus was the suggester of the 

 arrangement. Rheticus has preserved it as a saying of Co- 

 pernicus, that if he could only succeed in giving planetary 

 tables which should be true within ten minutes, he should 

 feel as much gratified as Pythagoras, when he discovered the 

 great property of the hypothenuse of a right-angled triangle. 



In this communication I have confined myself to points 

 which are either new, or very little known. I will add one 

 more circumstance of the latter kind. 



I have noted that Rheticus stands in the Index as damnatus 

 auctor^ while Copernicus is damnati libri auctor: a material 

 difference. But perhaps it may suggest itself to some that 

 Copernicus is only the writer of one work, which, being 

 condemned, makes him a condemned author; and that it 

 would not be thought necessary to condemn, in general terms, 

 a writer all whose works can be prohibited under one title. 

 But, not to dwell here upon such a supposition really imply- 

 ing an ignorance of the usage, it is not true that Copernicus 

 wrote and published only one work. Though it be but little 

 known, and not mentioned by any of the French school of 

 historians, it is certain that Rheticus himself published (Wit- 

 temberg, 1542) in 4to the " De lateribus et angulis triangu- 

 lorum tum planorum rectilineorum, tumsphaericorum libellus," 

 containing a table of sines to every minute, and to a radius of 

 ten millions, or as we should now say, to seven decimals. 



This work is mentioned by Weidler, who, though of Wit- 

 temberg, had no knowledge of it till he published the supple- 

 ments of his history : it is catalogued by Murhard, and de- 

 scribed by Kastner. The great work De RevolutionibuSf pub- 

 lished the next year, contains a probably abridged treatise on 

 triangles, and a certainly abridged table of sines. 



In speaking of the great work of Copernicus, it should be 

 remembered that Rheticus procured its publication, or ex- 

 tracted the author's consent to its appearance, as much as 



