W. A. Rogers on Variability of Personal Equation. 305 
Let us now consider certain variations of the personal equa- 
tion in which the condition of the observer is not taken into 
account, 
I', Does a “ee in the character of the —— of the 
wires affect the personal equat 
Bright wires minus faint wires. 
Dec. 22—= +°027'; Mee 4 faint. 
4 +4024; 
—'001 : 
28 0163 moderately faint. 
Jan. 13 +060; extremely faint. 
| WP. Does the —— equation vary between a natural and an 
4 urtificial illumination of the wires 
Natural minus artificial. 
May 26—-—-002° 
31 
- June 2° —-026 
4a 2-011 
2 —000 
These observations were made during the day time. The 
artificial illumination was produced in the way already described, 
clock-room being darkened, 
IIl?, Does the size of the sai ae affect the personal equa- 
x From Nov. 20, till Nov. 99, a five stars were employed, 
: the first one being larger than the others. 
4 R.—T. from Nov. 20 till Nov. 29. 
Large star. Small stars. 
—'2335 —'1445—*167°—153°— 166° 
La tar minus mean of small stars. 
Doeggei pels 152°)=-—08 1°. 
First wire sani each of the following wires from Nov. 20 till Nov. 29. 
+0528 s — -0408—-0225—-049— 0338 
EPs ee es =O, ee 
“085% 
ci must remark, ine that % ‘laid not find a well-defined 
Corresponding difference between bright and faint stars inthe 
observations for relative personal equation with the equatorial. — 
Ive -—Does a variation of the. 4s ernest penne? the wits a ae 
