Professor Tait pointed out two very simple ways of finding out whether a golf ball had its two centres approximately coincident, and whether in consequence it ought to and would fly well. The first was by floating it in a bath of brine or mercury and noticing whether it wobbled or turned over. Many golfers are acquainted with this test, and employ it in a cruder and less decisive form by floating the ball in water. While a ball that had a fairly considerable separation between its two centres might not show any wobbling movement when floated in water, and consequently might not completely establish its claim to be properly centered and of good flying capacity so far as this part of its properties was concerned, the presumption would be greatly in its favour. On the other hand, that which did show any perceptible wobble in water would be self-condemned at once, and would undoubtedly be a bad flyer and a danger to the game of the good golfer. The second test is one of comparison, and is exceedingly simple. You cannot compare the flying capacities of two or more balls by driving them with golf clubs, for however near to exact similarity you may think the strokes to have been, there is certain to have been an appreciable scientific and mathematical difference, such as would make a proper comparison impossible. But you may give practically exactly the same initial impetus in exactly the same circumstances to two or more balls by shooting them in the same direction from a crossbow, when the string is always pulled out to exactly the same point. Here you will have the balls flying under the simplest possible conditions, with no spin to complicate the flight and interfere with the comparison, and anyone who takes the trouble to make this experiment will find that some balls will regularly fly farther than others when shot forward in this manner. If the size and the weights are the same, these balls are better centered and better flyers, and it is an easy matter for any player to establish a standard by this test, and to judge of the perfection of any particular ball at a moment’s notice. Of course such a test takes no account of the resiliency of the ball; but then, as every player knows, there is a clear difference between good resiliency and good flying properties. In the old days of the gutta, when so much depended upon the even quality of the material all through the ball--and these were, of course, the days when Professor Tait made his investigations and experiments, and drew his conclusions--the variations between centres were greater than they are now, though not so great as in the early period of the rubber-core, when the winding and covering machinery were imperfect. Rubber-cored balls have lately begun to be covered by winding very thin strips of the covering material round the core in just the same way that the core itself is wound, and this should greatly conduce towards more accurate centering. An understanding of the foregoing will