472 Proceedings of the Royal Irish Academy. 



middle of the tube ; but what they were intended, for I cannot make 

 out. 



The other instrument of Ko Show-King, the Keen e, which I have 

 above likened to Tycho Brahe's armillse maximse, and which is by far 

 the more interesting of the two, is described at great length in the 

 Yuen She. It consists of a double declination circle, six feet in 

 diameter, each circle two inches wide, and an inch in thickness. The 

 interval between the two circles is one inch, and they are connected 

 at four points 90° apart. "The degrees and minutes" are marked 

 round the circumference (Father Matteo says, by prominent studs of 

 iron, which could be felt in the dark). There is no polar axis, but 

 two parallel stretchers, four inches on either side of the polar pivots, 

 and joined in the middle by a transversal brace, in the micldle of 

 which is the pivot for the alhidade. The latter has pointed ends and 

 two sights, with a round aperture in the middle, three-fifths of an 

 inch in diameter, "■ with a fiducial line down the centre." The 

 south-pole pivot is in the centre of a diurnal circle, also sis feet in 

 diameter, and divided into twenty-four hours. On this circle, which 

 is let into the mounting of the instrument, slides an equator-circle 

 of the same diameter, " divided into degrees and minutes, according 

 to the twenty-eight constellations." The following particulars I copy 

 verbatim from Mr. Wylie's translation : — " A hole is made through the 

 centre of the north-pole pivot. At the bottom of this hole a trans- 

 verse hole is drilled from side to side. A thread is passed up the 

 centre, bent over, and brought out at the two transverse holes, and 

 fastened at both sides. Three lengths of thread are passed through 

 the hole, and fastened. At the upper and lower ends respectively 

 threads are carried down to the two ends of the index bars {i.e. the 

 alidade), and passed through a hole, being sunk into the under side of 

 the index bar, along the centre line of which a groove is cut to 

 receive the thread. It is then carried along the middle of the slit to 

 the centre of the index bar, and through a hole in the middle part 

 the thread is passed up from the lower side of the index bar, and 

 fastened." 



This thread or wire has probably disappeared from the instrument 

 centuries ago. 



Mr. Wylie's Paper contains two lithographs of the two instru- 

 ments, but not seen from a good point of view, and consequently not 

 showing all the details well. I trust the reader will have learned 

 sufficient from the above descriptions to acknowledge the historical 

 interest attached to these old instruments, which anticipated some of 

 the ideas of the great Danish astronomer three centuries before his 

 time. 



