bright object, remarks, as friends always do, 'What beautiful colours!' Denning records a somewhat extreme case in which a friend, who had been accustomed to observe with a refractor, absolutely resented the absence of the familiar colour fringe in the picture given by a reflector, which is the true achromatic in nature, though not in name. The beginner is recommended to read the article 'The Adjustment of a Small Equatorial,' by Mr. E. W. Maunder, in the _Journal of the British Astronomical Association_, vol. ii., p. 219, where he will find the process of testing described at length and with great clearness. In making these tests, allowance has, of course, to be made for the state of the atmosphere. A good telescope can only do its best on a good night, and it is not fair to any instrument to condemn it until it has been tested under favourable conditions. The ideal test would be to have its performance tried along with that of another instrument of known good quality and of as nearly the same size as possible. If this cannot be arranged for, the tests must be made on a succession of nights, and good performance on one of these is sufficient to vindicate the reputation of the glass, and to show that any deficiency on other occasions was due to the state of the air, and not to the instrument. Should his telescope pass the above tests satisfactorily, the observer ought to count himself a happy man, and will until he begins to hanker after a bigger instrument. The mention of the pointing of the telescope to a star brings up the question of how this is to be done. It seems a simple thing; as a matter of fact, with anything like a high magnifying power it is next to impossible; and there are few things more exasperating than to see a star or a planet shining brightly before your eyes, and yet to find yourself quite unable to get it into the field of view. The simple remedy is the addition of a finder to the telescope. This is a small telescope of low magnifying power which is fastened to the larger instrument by means of collars bearing adjusting screws, which enable it to be laid accurately parallel with the large tube (Fig. 10). Its eye-piece is furnished with cross-threads, and a star brought to the intersection of these threads will be in the field of the large telescope. In place of the two threads crossing at right angles there may be substituted three threads interlacing to form a little triangle in the centre of the finder's field. By this device the star can always be seen when the glass is being pointed instead of being hidden, as in the other case, behind the intersection of the two threads. A fine needle-point fixed in the eye-piece will also be found an efficient substitute for the cross-threads. In the absence of a finder the telescope may be pointed by using the lowest power eye-piece and substituting a higher one when the object is in the field; but beyond question the finder is well worth the small