4 Astronomical Instrument of the Ancient Irish. 
our excellent friend and zealous antiquary, the Dean of St. Patrick’s. If I am not 
greatly mistaken, it is a Celtic astronomical instrument, invented to exhibit to the 
pupil a diagram of the earth’s polar inclination, and the phenomena of the phases of 
the moon. It is certainly a rude effort, but it displays considerable ingenuity, and a 
progress, or, at least an attempt, towards demonstration. It is very nearly the diagram 
now made use of, in elementary works on astronomy, for the same purpose. 
People possessing so correct a notion of the heavenly bodies, and skill to form 
an instrument so nearly representing their motions and real state, were, at all events, 
a discriminating race. It required a long period of study, a succession of ages of 
learning, with a state of quietude and undisturbed repose, to have arrived at such a. 
point of scientific knowledge. 
It is of Celtic brass, and evidently was in common use ; for though parts of many 
have been found, no other, as far as I have seen, was perfect. It consists of a circle, the 
outside edge of which represents the moon’s orbit, having on it eight rings _represent- 
ing the different phases of the planet. In the inside of this circle, is another fixed 
on an axis, in the line of the inclination of the poles, on which this, which represents 
the earth, traverses, 
FIRST QUARTER, 
NEW 
jy MOON. 
SUPPOSED 
POSITION OF 
THE SUN. 
LAST QUARTER, 
eee oe 
