Made by William Currie & Company, Eclipse Patent balls were produced under the third patent ever issued for a golf ball,  William Currie’s Dec 20, 1877 British Patent 4,838.  This patent covered including additives mixed into the gutta percha, such as ground cork, ground leather, vegetable fibers, etc.   The fact that the Eclipse is not made from pure gutta percha makes it a composite ball, although the actual ingredients and amounts included in the various Eclipse balls are not known.

This Eclipse composite gutty golf ball dates to 1889.  Currie made slightly different versions of the Eclipse into the early 1890s.  This 1889 example appears unused and still retains most of its original paint.

Eclipse ball is second from the left in the top row of the accompanying group photo