VOL. LXIV.] PHILOSOPHICAL TKAN8ACTIONS. 493 



There was besides another telescope of 8 feet, consisting of 2 object-glasses, in 

 the manner of Roemer, which might be brought nearer together or separated, 

 in order that the moon's diameter might completely fill a fine reticule, in the 

 focus, divided into J 2 equal parts, for measuring the digits eclipsed in lunar 

 eclipses. It is mentioned in the account of the lunar eclipse of Nov. 12, 1761, 

 that the clock was regulated by a transit instrument. It is therefore probable 

 it was regulated in the same manner in all the succeeding observations, which 

 consist of the following particulars: 



1 . Observations of the last transit of Venus over the sun, viz. of differences 

 of right ascension and declination between Venus and the sun, and the internal 

 and external contact of the limbs at the egress. It is however remarked, that 

 the clock was counted by a person, who was sometimes found to make mistakes. 

 — 2. The eclipse of the sun. May 25, 1770. The beginning and end were ob- 

 served, and the lucid parts measured, during the eclipse, with the micrometer. 

 — 3. The beginning and end of the eclipse of the moon, Oct. 23, 1771- — 4. 

 Emersion of Jupiter from occultation by the moon, July 5, 1770. — 5. An oc- 

 cultation of Spica Virginis by the moon; the immersion and emersion both ob- 

 served Jan. 25, 1772. — 6. The occultation of a star in Scorpio by the moon; 

 the immersion and emersion both observed. — 7. The observation of Venus in 

 the sun's parallel, Jan. 5, 1772, by taking the difference of right ascension and 

 declination of Venus and the sun. — 8. The total eclipse of the moon, Nov. 12, 

 1761. The beginning, total immersion, emersion, and end, were observed by 

 3 different observers, with telescopes of 5, 7> and 8 feet, in the domestic obser- 

 vatory of the College of the Jesuits ; where also all the former observations were 

 made. The same eclipse was also observed at the Royal Observatory at Pekin, 

 14* west of the Jesuit's College, with a telescope of 8 feet, composed of 2 ob- 

 ject-glasses, with a reticule at the focus, divided into 12 equal intervals for mea- 

 suring the digits eclipses, in the manner of Roemer. It is remarked, that the 

 leaf, in which this observation was recorded, had been lost, and was found again, 

 Oct. 12, 1772; on which account this observation was never transmitted to 

 Europe before. Nevil Maskelyne. 



The observations themselves are however omitted, being not now of any fur- 

 ther use. 



///. The Lunar Eclipse, Oct. 11, 1772, observed at Canton. Communicated 

 by John Blake, Esq., of Parliament-street, p. 46. 

 The time being taken only by a watch regulated by the sun the day before, 

 the observation is not much to be depended on. Nevil Maskelyne. 



IV. Experiments on Dying Black. By Mr. James Clegg, of Redivales, near 



Bury. p. 48. 

 Lime having been proved to increase the solvent power of water, on astringent 



