"The Larger Of These Instruments Were Four In Number.

First we inspected a great globe [A], graduated with meridians and parallels; we estimated that three men would hardly be able to embrace its girth....

A second instrument was a great sphere [B], not less in diameter than that measure of the outstretched arms which is commonly called a geometric pace. It had a horizon and poles; instead of circles it was provided with certain double hoops (armillae), the void space between the pair serving the purpose of the circles of our spheres. All these were divided into 365 degrees and some odd minutes. There was no globe to represent the earth in the centre, but there was a certain tube, bored like a gun-barrel, which could readily be turned about and fixed to any azimuth or any altitude so as to observe any particular star through the tube, just as we do with our vane-sights;[8] - not at all a despicable device! The third machine was a gnomon [C], the height of which was twice the diameter of the former instrument, erected on a very large and long slab of marble, on the northern side of the terrace. The stone slab had a channel cut round the margin, to be filled with water in order to determine whether the slab was level or not, and the style was set vertical as in hour-dials.[9] We may suppose this gnomon to have been erected that by its aid the shadow at the solstices and equinoxes might be precisely noted, for in that view both the slab and the style were graduated. The fourth and last instrument, and the largest of all, was one consisting as it were of three or four huge astrolabes in juxtaposition [D]; each of them having a diameter of such a geometrical pace as I have specified. The fiducial line, or Alhidada, as it is called, was not lacking, nor yet the Dioptra.[10] Of these astrolabes, one having a tilted position in the direction of the south, represented the equator; a second, which stood crosswise on the first, in a north and south plane, the Father took for a meridian; but it could be turned round on its axis; a third stood in the meridian plane with its axis perpendicular, and seemed to stand for a vertical circle; but this also could be turned round so as to show any vertical whatever. Moreover all these were graduated, and the degrees marked by prominent studs of iron, so that in the night the graduation could be read by the touch without a light. All this compound astrolabe instrument was erected on a level marble platform with channels round it for levelling. On each of these instruments explanations of everything were given in Chinese characters; and there were also engraved the 24 zodiacal constellations which answer to our 12 signs, 2 to each.[11] There was, however, one error common to all the instruments, viz. that, in all, the elevation of the Pole was assumed to be 36 deg.. Now there can be no question about the fact that the city of Nanking lies in lat. 32-1/4 deg.; whence it would seem probable that these instruments were made for another locality, and had been erected at Nanking, without reference to its position, by some one ill versed in mathematical science.[12]

[Illustration: Observatory Terrace]

[Illustration: Observatory Instruments of the Jesuits.]

"Some years afterwards Father Matteo saw similar instruments at Peking, or rather the same instruments, so exactly alike were they, insomuch that they had unquestionably been made by the same artist. And indeed it is known that they were cast at the period when the Tartars were dominant in China; and we may without rashness conjecture that they were the work of some foreigner acquainted with our studies. But it is time to have done with these instruments." - (Lib. IV. cap. 5.)

In this interesting description it will be seen that the Armillary Sphere [B] agrees entirely with that represented in illustration facing p. 450. And the second of his photographs in my possession, but not, I believe, yet published, answers perfectly to the curious description of the 4th instrument [D]. Indeed, I should scarcely have been able to translate that description intelligibly but for the aid of the photograph before me. It shows the three astrolabes or graduated circles with travelling indexes arranged exactly as described, and pivoted on a complex frame of bronze; (1) circle in the plane of the equator for measuring right ascensions; (2) circle with its axis vertical to the plane of the last, for measuring declinations: (3) circle with vertical axis, for zenith distances? The Gnomon [A] was seen by Mr. Wylie in one of the lower rooms of the Observatory (see below). Of the Globe we do not now hear; and that mentioned by Lecomte among the ancient instruments was inferior to what Ricci describes at Peking.

I now transcribe Mr. Wylie's translation of an extract from a Popular Description of Peking:

"The observatory is on an elevated stage on the city wall, in the south-east corner of the (Tartar) city, and was built in the year (A.D. 1279). In the centre was the Tze-wei[13] Palace, inside of which were a pair of scrolls, and a cross inscription, by the imperial hand. Formerly it contained the Hwan-t'ien-e [B] 'Armillary Sphere'; the Keen-e [D?] 'Transit Instrument' (?); the Tung-kew [A] 'Brass Globe'; and the Leang-t'ien-ch'ih, 'Sector,' which were constructed by Ko Show-king under the Yuen Dynasty.

"In (1673) the old instruments having stood the wear of long past years, had become almost useless, and six new instruments were made by imperial authority. These were the T'ien-t'ee 'Celestial Globe' (6); Chih-taoue 'Equinoctial Sphere' (2); Hwang-taoue 'Zodiacal Sphere' (1); Te-p'ing kinge 'Azimuthal Horizon' (3); Te-p'ing weie 'Altitude Instrument' (4); Ke-yene 'Sextant' (5). These were placed in the Observatory, and to the present day are respectfully used.

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