780 
Ancient Observatory at Delhi . [December, 
wall, and, carried up vertically, give the cog-wheel-like 
appearance to the inner plan of the towers, as noticed when 
looking down on them from the gnomon. On each side of 
these recesses are pigeon-holes, of a convenient size for the 
feet, so that, by straddling across from side to side, an 
observer can easily mount, resting his back against the wall, 
up to the top, and bring his eye with ease to the edge on 
either side, on which are marked the angles of depression 
from the edge of the flat top of the centre pillar. Along 
these vertical edges the degrees are numbered in Hindoo 
(Sanscrit), not Arabic figures, the Zero being at the top, 
and the 45th degree at the angle where the vertical and 
horizontal portions of fine work meet (see the angle marked 
G in Fig. 2). The Zero point (c, Fig. 2) was in every case 
removed. (Every fifth degree was marked in figures, the 
others by a line only.) I walked round the summit of each 
tower to assure myself of this, as I was anxious to find one 
in situ . It had apparently been marked by the edge of a 
stone about a foot square, and so would be a convenient 
size for grinding curry-stuff on. Such stones are in daily 
use by all the inhabitants of the country, and being ready 
cut and levelled would naturally be soon appropriated. And 
the flight of pigeon-holes led dire< 5 tly up to them. 
Each of the observing recesses had three windows, lancet- 
shaped, together forming three rows of windows round each 
tower : they were of no apparent value, and were draughty 
and dangerous for an observer. Some were bricked up, and 
I regret I did not record the position of these, as it might 
have given an idea of the direction from which observations 
were most frequently taken. 
The eighteen spokes being of the same width as the inter- 
vals between them, it follows that the circular floor was 
divided into thirty-six equal divisions of 10 degrees each. 
And now we learn the value of the two towers — as the 
raised “ spokes,” or “ sedtors ” as we shall prefer to call 
them, in one occupied the place of the unmarked floor in 
the other. Each of these raised sedtors, and the vertical 
wall adjoining them, had been once covered with the fine 
“ ivory ” cement I have spoken of. But little of it remains 
on the broad surfaces, as it seemed to have suffered from 
the weather and the frosts not uncommon here in January 
and February ; though in the salient angles formed by the 
recesses I have mentioned it was more perfedt than else- 
where, and the lines and figures on it were generally legible. 
They had apparently been drawn by some blunt fine-pointed 
instrument before the cement was quite dry. Each sedtor 
