“Besides this in a lower hall they had established a gnomon....  This observatory, not worthy of much consideration for its ancient instruments, much less for its situation, its form, or its construction, is now enriched by several bronze instruments which Father Verbiest has placed there.  These are large, well cast, adorned in every case with figures of dragons,” etc.  He then proceeds to describe them: 

“(1).  Armillary Zodiacal Sphere of 6 feet diameter.  This sphere reposes on the heads of four dragons, the bodies of which after various convolutions come to rest upon the extremities of two brazen beams forming a cross, and thus bear the entire weight of the instrument.  These dragons ... are represented according to the notion the Chinese form of them, enveloped in clouds, covered above the horns with long hair, with a tufted beard on the lower jaw, flaming eyes, long sharp teeth, the gaping throat ever vomiting a torrent of fire.  Four lion-cubs of the same material bear the ends of the cross beams, and the heads of these are raised or depressed by means of attached screws, according to what is required.  The circles are divided on both exterior and interior surface into 360 degrees; each degree into 60 minutes by transverse lines, and the minutes into sections of 10 seconds each by the sight-edge[2] applied to them.”

Of Verbiest’s other instruments we need give only the names:  (2) Equinoxial Sphere, 6 feet diameter. (3) Azimuthal Horizon, same diam. (4) Great Quadrant, of 6 feet radius. (5) Sextant of about 8 feet radius. (6) Celestial Globe of 6 feet diameter.

As Lecomte gives no details of the old instruments which he saw through a grating, and as the description of this zodiacal sphere (No. 1) corresponds in some of its main features with that represented in the photograph, I could not but recognize the possibility that this instrument of Verbiest’s had for some reason or other been removed from the Terrace, and that the photograph might therefore possibly not be a representation of one of the ancient instruments displaced by him.[3]

The question having been raised it was very desirable to settle it, and I applied to Mr. Wylie for information, as I had received the photographs from him, and knew that he had been Mr. Thomson’s companion and helper in the matter.

“Let me assure you,” he writes (21st August, 1874), “the Jesuits had nothing to do with the manufacture of the so-called Mongol instruments; and whoever made them, they were certainly on the Peking Observatory before Loyola was born.  They are not made for the astronomical system introduced by the Jesuits, but are altogether conformable to the system introduced by Kublai’s astronomer Ko Show-king....  I will mention one thing which is quite decisive as to the Jesuits. The circle is divided into 365-1/4 degrees, each degree into 100 minutes, and each minute into 100 seconds.  The Jesuits always used the sexagesimal division.  Lecomte speaks of the imperfection of the division on the Jesuit-made instruments; but those on the Mongol instruments are immeasurably coarser.