[ j s 6 ] 
pendulum or clock was one with weights. He fays 
he regulated his clock by equal altitudes, and then 
by meridional pafiages of Spica Virginis, and of the 
Sun ; but why did he leave off the method of the 
equal altitudes which he made ufe of at firft, and in 
what manner did he obferve thefe altitudes to deter- 
mine the paflage either of a fixed flar or of the Sun 
over the meridian ? It does not appear that he had 
a quadrant or tranfit inftrument. I am forry that 
this uncertainty about the means employed by Mr. 
Hirff to determine the time of the phafes puts it out 
of my power to make ufe of an obfervation, which 
might otherwife have been extremely ufeful, had the 
aftronomer been equally well provided with inftru- 
ments as he appears to have knowledge and zeal. 
It is to be obferved that by increafing or diminifhing 
by io" the duration obferved at Madrafs, the quef- 
tion of the parallax will be decided conformably ei- 
ther to the obfervation of Rodriguez or that of the 
Cape. 
In the fame volume of the Tranfadtions, are fome 
obfervations of the fame tranfit made at Abo and at 
Hernofand ; the total duration was obferved in both 
places ; it may have been lengthened fomewhat be- 
yond its limits ; but thefe obfervations agree at leaf! 
in this point with all the others that were made in 
the North, viz. that being compared with the To- 
bolfk obfervation, with regard to the duration of the 
tranfit, they give above i o" for the horizontal par- 
allax of the Sun. 
I have likewife lately had the communication of 
Mr.Rumowfki’s obfervation made at Selenginfk in Si- 
beria. 1 fliall not expatiate upon the particulars here, 
2 fuppofing 
