656 PHILOSOPHICAL TRANSACTIONS. [aNNO I769. 



plan. The corresponding altitudes, for determining the time of the observations 

 of the transit of Venus, were taken, by reflection, from a basin of quicksilver 

 or treacle, with a brass Hadley's sextant, made by Mr. Ramsden ; the surface of 

 the fluid being defended from the wind by a glass ground truly plane. They 

 find that the equal altitudes seldom differ above 2 or 3 seconds in determining 

 the time of noon ; so that, by taking a great many at once, and taking the 

 mean, they think they cannot fail of coming very near the truth. Mr. M. 

 examined the equal altitudes made about the time of the transit, and the times 

 of the contact are given corrected in the foregoing account. The clock in the 

 observatory seems to go pretty well, though it only beats dead quarter seconds ; 

 it has a mahogany pendulum, and was made by Mr. Cummins. In the house 

 was a clock beating seconds, and set, by means of the other, in the afternoon, 

 before the beginning of the transit. The latitude of the place was also deter- 

 mined by meridian altitudes, taken by reflection with the sextant, and, by the 

 mean of 10 observations, which all agree within the compass of 2 minutes, is 

 55° 57' 37" N. The end of the solar eclipse was observed by two persons with the 

 two achromatic telescopes, with treble object glasses, and they agreed to a 

 second. 



Dr. Lind writes, another time, that, being from home, at Lees, near Cold- 

 stream, 7 miles west of Berwick, he observed the latitude of the place about 

 55° 37'. 



The foregoing particulars are extracted from letters received from Dr. Lind. 

 He has also communicated the following observations of the transit of Venus and 

 solar eclipse, made by the Rev. Mr. Brice, at Kirknewton. 

 ; He is a very good astronomer, and is a writer in the Phil. Trans. Kirknewton 

 is in lat. 55° 54' 30'' n. and about 17 miles w. of Hawkhill, from measuring it 

 on Lawrie's map of the environs of Edinburgh. The clock had been tried by 

 several transits of a fixed star, and always found to measure time so exactly, 

 that in the space of 5 days it did not differ one second from the truth ; it was 

 also examined by taking equal altitudes of the sun, and found to be 18 slow. 

 The day was cloudy, with flying showers, till about 2 o'clock in the afternoon ; 

 then it grew somewhat clear, and about 4 the sun shone out exceedingly bright, 

 when he observed carefully the spots on the sun ; the brightness continued till 

 about 15" before ^^, when a cloud came over the sun, which was not seen till 

 &" 55"" 40' mean time, as shown by the clock, and then Venus had made a sen- 

 sible impression on the upper limb of the sun's zenith, and -^, as he judged, 

 on the sun. 



Half on the sun, as he thought, 7' 3"" 55' 



Internal contact clearly seen 7 1 1 53 



1 8' added for the clock too slow + 18 



Makes 7 12 13 



