390 MESSES. DE LA KITE, STEWART, AND LOEWY’S KESEAKCHES 
the series; and although in the beginning of 1832 the size of the disk was slightly less, 
being about 1-80 inch, we have thought it unnecessary to take account of this. We 
have therefore supposed that for all the observations of Schwabe discussed in this 
research the scale of delineation remained unaltered. 
Previous to 1840 the disk was divided into four quarters by a vertical and horizontal 
diameter, but after 1840 there were drawn in addition four other lines forming a square 
inscribed in the circle, and having horizontal and vertical sides, and this square was by 
means of the two diameters cut into four smaller squares. It is possible that by this 
arrangement the position of a group on the solar disk might be more accurately ascer- 
tained ; nevertheless we have not hesitated to commence our research from the year 
1832. 
22. From 1832 to 1854 Schwabe has the merit of being the only systematic observer 
of the solar disk. In November 1853 Carrington began his observations, while in 
February 1862 the Kew Heliograph was in regular operation under the direction of 
Mr. Warren He La Rue. Adopting the photographic pictures taken with the Kew 
instrument as the standard of accuracy, we have already shown that Carrington’s results 
are almost equally trustworthy. It will therefore be necessary to compare Schwabe’s 
results with those of Carrington and with the Kew series in order to test their accuracy. 
23. In reducing Schwabe’s drawings we proceeded in the following manner. Selecting 
an arbitrary scale, the same individual measured in terms of the scale the area of every 
group given by Schwabe, and occasionally during the operation (which occupied some 
time) he took pains to ascertain that his mode of estimation remained unaltered. We 
were thus furnished with a series of results which were probably affected throughout 
with the same personal peculiarity, but which, being founded upon an arbitrary scale, it 
was necessary to connect by means of a proper multiplier with that scale which we have 
hitherto adopted, of which the unit is one-millionth of the sun’s visible hemisphere. 
24. The following Table will elucidate this step in the process of reduction. 
Table IV. — Comparison of results derived from Schwabe by the arbitrary scale, with 
simultaneous results derived from Carrington’s observations and from the Kew 
series. 
Date. 
Schwabe. 
Carrington. 
Date. 
Schwabe. 
Kew. 
1854. 
1862. 
Deo. 1-15 
2-7 
105 
April 20 to May 1 
11-9 
698 
Nov. 16-30 
9'5 
565 
1863. " 
Sept. 1-15 
3-4 
215 
.Tan. 1—15 
21-6 
1511 
Sept. 16-30 
2-3 
138 
Jan. 1 6—31 
15-7 
901 
1859. 
May 1-15 
13-5 
622 
Dec. 1-15 
18-2 
] 
May 16-31 
13*3 
812 
Dec. 16 31 
16-4 
1060 
76-0 
4544 
52-5 
3305 
From the left-hand series we derive 65 as the multiplier to be applied to Schwabe’s 
