The writer lays no claim to having originated this method, it having been suggested in the summer of 1900 by Lieutenant-Commander W. I. Chambers, U. S. N., and used at that time aboard both the Texas and Massachusetts. Whether or not it is original with that officer is not known, but the writer has never been able to discover it in print and deems it worthy of being put into such shape as to be readily accessible to the service at large. Hence the preparation of this article.
In the description that follows, the case of the U. S. S. Massachusetts has been taken, the observations being made some miles to the eastward of Boone Island Light, off the coast of Maine. In this method three observers are necessary as follows: