In a paper I had read at the Royal United Service Institution I made mention of its value to navigation, and some little time after this I was asked by the inventor, then Sir William Thomson, if I would testify to this in a case that he was bringing before the law courts to stop the infringement of his patent right. I was able to state the following-- Between the longitudes I have mentioned the variation of the compass or magnetic variation changes from about 30° W. to 10° E., for the locality is in the vicinity of the centre from which the variation lines radiate. It was consequently necessary to alter the compass course at stated times to maintain the due east tract we wished to take, and at certain times the alteration of a degree was made every two, three, or four hours. My last observation showed Lat. 45° 58’, the next one 45° 53’, so that in the ten days, run without sights, we were only five miles out in our latitude. To be called as an expert witness in such an interesting case as this one was, is not a disagreeable experience. It was then that I first met Sir John Fisher, now Lord Fisher, who with Admiral Hotham and two staff-captains were subpœnaed to represent the Navy. I fancy that Sir Charles Hotham was then one of the Sea Lords, and Lord Fisher was then a Captain. Captain Squire Lecky, the author of _Wrinkles in Navigation_, and myself stood for the merchant service. It was the time of the Parnell trial, and the present Lord Chief Justice, who represented the Crown in that inquiry, was secured by Sir William Thomson to take charge of his case. I must confess that all we sailors were looking forward with a kind of amused interest to see what the lawyers would do when dealing with the magnetism of iron ships, and as it happened I had one of the treats of my life. Sir Richard Webster, as he then was, coming in fresh from the Parnell case, proceeded to explain, in words that were to be understood by all, the theory of the deviation of the compass in iron or steel ships, the defects of compasses prior to Sir Wm. Thomson’s, and the advantages to which his invention had given birth--all this in the clearest possible language and with the most convincing mastery. He spoke one whole day and part of the next, and, so far as I personally was concerned, taught me more about what I considered was a special subject of my own than I ever knew before. Sitting near Lord Alverstone at dinner some little time since, I reminded him of the case, and he said it was an agreeable change, at the time, to the other case he was engaged on. Sir William Thomson won his case and wrote me a letter of cordial thanks for the help I had given him in the matter. The most humorous thing in that trial was the spectacle of Captain John Fisher in the witness-box in the dusk of an autumn afternoon, looking like a school-boy, and suggesting by his demeanour that so far as he knew anything, green grass was his colour. But he recalled a youthful episode of a piece