A'OL. LXVII.] PHILOSOPHICAL TRANSACTIONS. 215 



large stones that composed them, and in the joining and fastening them into 

 each other by means of lead and iron cramps. 



The situation of the two large quadrants of the instrument marked a in pi. 3, 

 whose radius is 9 feet 2 inches, by being at right angles with a gnomon at 25 

 degrees elevation, are thrown into such an oblique situation as to render them 

 the most difficult, not only to construct of such a magnitude, but to secure in 

 their position for so long a period, and affords a striking instance of the ability 

 of the architect in their construction ; for, by the shadow of the gnomon thrown 

 on the quadrants, they do not appear to have altered in the least from their 

 original position; and so true is the line of the gnomon, that, by applying the 

 eye to a small iron ring of an inch diameter at one end, the sight is carried 

 through 3 others of the same dimension to the extremity at the other end, 

 distant 38 feet 8 inches, without obstruction; such is the firmness and art with 

 which this instrument has been executed. This performance is the more 

 extraordinary when compared with the works of the artificers of Hindostan at 

 this day, who are not under the immediate direction of a European mechanic; 

 but arts appear to have declined equally with science in the east. 



Liet. Col. Arch. Campbell, at that time chief engineer in the East- India 

 Company's service at Bengal, a gentleman whose abilities do honour to his pro- 

 fession, made a perspective drawing of the whole of the apparatus that could be 

 brought within his eye at one view; but I lament he could not represent some 

 very large quadrants, whose radii were about 20 feet, being on the side whence 

 he took his drawing. Their description however is, that they are exact quarters 

 of circles of different radii, the largest of which I judged to be 20 feet, con- 

 structed very exactly on the sides of stone walls built perpendicular, and situated, 

 I suppose, in the meridian of the place: a brass pin is fixed at the centre or 

 angle of the quadrant, from which the Bramin informed me they stretched a 

 wire to the circumference when an observation was to be made; from which it 

 occurred to me, the observer must have moved his eye up or down the circum- 

 ference, by means of a ladder or some such contrivance, to raise and lower 

 himself, till he had discovered the altitude of any of the heavenly bodies in their 

 passage over the meridian, so expressed on the arcs of these quadrants: these 

 arcs were very exactly divided into 9 large sections; each of these again into 10, 

 making 90 lesser divisions or degrees; and those also into 20, expressing 3 

 minutes each, of about ^V of an inch asunder; so that it is probable, they had 

 some method of dividing even these into more minute divisions at the time of 

 observation. 



My time would only permit me to take down the particular dimensions of the 

 most capital instrument, or the greater equinoctial sun-dial, represented by 

 figure A, plate 3, which appears to be an instrument to express solar time by the 



