VOL. XV.] PHILOSOPHICAL TRANSACTIONS. 217 



printing-houses, with the furniture thereof, and great part of his library ; also 

 the remaining copies of all his printed works, published at his own expence, 

 from the year 1647 to 1679, and particularly his dear Urania, and all its obser- 

 vatories, with all his instruments, astronomical and optical, and many other 

 things of great worth, were in a manner wholly consumed, and reduced to 

 ashes. He is thankful however that, before this calamity, he had, the same 

 year, finished and published the latter part of his Machina Coelestis, contain- 

 ing the observations of almost 50 years, and which are thereby preserved : that 

 some of his papers, particularly his new catalogue of the fixed stars, were 

 wonderfully preserved from the fire : and, that he has taken courage to resume 

 his former studies, to rebuild his observatory, and furnish it with necessary in- 

 struments, though much inferior to those incomparable ones that perished by 

 the fire ; and to apply himself to deduce a-new, from their first originals, much 

 of what was destroyed relating to his Prodromus Astronomiae, his correction of 

 the tables, his Uranographia, and his new celestial globes. 



This present piece, the first published by him since that dreadful conflagra- 

 tion, he calls his Annus Climactericus, being the 49th year of his observations, 

 and because of that great revolution of affairs which in that year befel him ; the 

 beginning of which, and the greatest part of it, being much to his content, 

 but the end of it so sad and dismal. 



Among the happinesses of that year, he reckons, first, his finishing and 

 publishing the latter part of his Machina Coelestis, containing the observations 

 of 48 years. And then Mr. Halley's visit to him at Dantzic, for some months ; 

 and the great satisfaction it afforded him. Having before much desired that 

 some such skilful person from the Royal Society at London, acquainted with 

 the way of observing there, by telescopic sights, might repair to him at Dantzic, 

 to witness the manner of liis observing, by plain sights, and the naked eye. 

 Who, having thus been an eye-witness of both ways, might satisfy that Society 

 of the comparative merits of both; at least, that his way of observing was not 

 so despicable as might by some be thought or pretended. And he particularly 

 rejoices that the observations then made in Mr. Halley's presence, and with his 

 assistance, were wonderfully preserved from the fire, by which so many other 

 things perished. 



For there had some years before happened a controversy between Mr. Hook 

 and him, by letters, concerning the excellency of telescopic sights, which Mr. 

 Hook much preferred before the plain sights, used by Tycho, by the Landgrave, 

 by all observers heretofore, and by this author ; as if it were not possible, with 

 these sights, to make observations nearer than to 2 or 3 whole minutes : 

 whereas he alleges, that himself with telescopic sights, by an instrument onlj 



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