APPENDIX
THE GEOMETRY OF THE EPEIRA'S WEB
I FIND myself confronted with a subject which is not only highly interesting, but somewhat difficult: not that the subject is obscure; but it presupposes in the reader a certain knowledge of geometry: a strong meat too often neglected. I am not addressing geometricians, who are generally indifferent to questions of instinct, nor entomological collectors, who, as such, take no interest in mathematical theorems; I write for any one with sufficient intelligence to enjoy the lessons which the insect teaches.
What am I to do? To suppress this chapter were to leave out the most remarkable instance of Spider industry; to treat it as it should be treated, that is to say, with the whole armoury of scientific formulæ, would be out of place in these modest pages. Let us take a middle course, avoiding both abstruse truths and complete ignorance.
Let us direct our attention to the nets of
383
