ASTRONOiMY IN WANSTKAI). 1 59 



the disc of the planet," "Observations made with Mr. Hadley's 

 reflecting Telescope," etc., etc., may be found in the Phil. Trans., 

 vols. xxix. to xxxii. 



His collections of Natural History were presented to the 

 Ashmolean Museum, Oxford. 



After the death of Dr. Pound, his widow left the rectory, 

 removing to a small house on her brother's estate. The (irove. The 

 house adjoined the stables, and was just behind the Clock House 

 (Capt. Kindersley's). 



Here, when free from his studies at Oxford, Dr. Bradley resided, 

 and " observed at his Aunt Pound's house in Wanstead Town, " 

 beginning in July, 1725. He tells us "the house was small, the 

 ground room only 7^ feet high, with a loft or garret over it." 



It was in the upper part of this house he had on the 19th 

 August, 1727, a zenith sector, of 12^ feet radius and i2|^' range, 

 mounted for him by Graham ; even the Observatory at Greenwich 

 did not possess one till Bradley's was removed there in 1749. 



In January, 1730, he propounded his theory of the aberration of 

 the fixed stars, containing the important discovery of the aberration 

 of light. He is said to have been led to this, when sailing on the 

 Thames, by remarking "that every time the boat put about, the 

 vane at the top of the boat's mast shifted a little, as if there had 

 been a slight change in the direction of the wind. He observed 

 this three or four times without speaking ; at last he mentioned it 

 to the sailors, and expressed surprise that the wind should shiit 

 so regularly every time they put about. The sailors told him the 

 wind had not shifted, but that the apparent change was owing to the 

 change in the direction of the boat, and that the same thing invari- 

 ably happened." (Thomson, " History of the Royal Society." ) 



From this he inferred that the direction in which we see a star, 

 is not that in which it actually lies, but is inclined to it by an angle 

 depending on the direction of the earth's motion round the sun at 

 the time, and the ratio of its velocity to that of light. 

 ■ For this discovery he was complimented by the Royal Society, 

 who discharged him from all future payments. 



In the year 1732 his aunt removed with him to Oxford, and he 

 transferred most of his instruments, leaving, however, the zenith 

 sector, as he was then engaged in making an extended investigation, 

 and for the next fifteen years frequently visited Wanstead for the 

 purpose. The result was his great discovery — a discovery which 



