The rigging of aeroplanes, although not a subject necessitating extensive research work or particular scientific knowledge, is of paramount importance, in view of its effect on the safety, reliability, and performance of machines.

The mechanical principles involved are well known to the engineer, and their application rests to a great extent on experience.

In a word, practicability governs both construction and erection.

The strength of wooden struts consisting of a parallel centre portion with ends of conical taper is considered rnathematically. It is shown that the best results are obtained when the parallel portion is half the total length of the strut, and when the taper of the ends is such that the end diameter is half the central diameter. Such a strut is 12% lighter than a simple parallel strut of the same length and strength, and only 1% heavier than the ideal strut of the best possible gradual taper. A simple formula for design is given.

The authors suggest that struts of this pattern might be adopted, for manufacture reasons, in many parts of an aeroplane in which solid wooden struts are used, especially if of circular section. They can then be turned in the ordinary lathe.