162 ROYAL SOCIETY OF CANADA 



and if this curve be produced, as are the curves of the charts of the pre- 

 sent day it will touch the west coast of Ireland. My answer, therefore, to 

 Mr. Harrisse is that, in measuring the length of the line of divergence 

 south of a due west course, we must commence in the case of Cabot near 

 the coast of Ireland, and in the case of Columbus at a considerable dis- 

 tance west of Gomera ; and it must be observed also that it was not 

 until he reached longitude 40** that the admiral noticed a variation of a 

 full point. 



Resuming the argument from the uniformity of nature, I would 

 invite attention to the charts of the present day, by which it will appear 

 that a course west from the coast of Ireland cuts the lines of magnetic 

 variation in quick succession, while, farther south, they widen out, so 

 that, in the south, a vessel in the last of its course is sailing on the circum- 

 ference of a curve and towards a lesser variation, while, at the north, she 

 is sailing constantly towards an increasing variation. This must have 

 been relatively the case also 400 years ago, though to a lesser absolute 

 degree. The amount of variation was less, but the relative variation 

 would have been proportionate. 



Returning now to Mr. Harrisse's mathematical demonstration, it 

 will appear that from his sum total of 8,150 miles ^' must be deducted at 

 least 6*72 miles, leaving a distance of 2,478 miles ; but, by the admiral's 

 course, as worked out by Capt. Fox, the distance was only 3,105 miles,^" 

 80 that at the outside only 2,433 miles were sailed subject to westerly 

 variation. In the case of Cabot, however, sailing on a parallel twenty- 

 three degrees farther north, the line of westerly variation would be crossed 

 close to the coast of Ireland. His whole course on the Atlantic would 

 be subject to this disturbing influence. The distance from that coast, at 

 latitude 53° to Cape Race is not 1,600 but 1,*740 miles, as carefully 

 measured on an Admiralty chart, and the admiral's course, subject to 

 westerly variation, was 684 miles longer. Cabot, on a northern parallel, 

 would, of necessity, cross the magnetic meridians in quicker succession, 

 and the proportionate degree of variation would be probably correct, as 

 stated in my first paper. Mr. Harrisse is quite right in stating that 

 the conditions of the two courses were ditferent, but he is not correct, 

 however, in thinking that my " belief that the landfall actually was at 

 " Cape Breton rests mainly on this supposition." It rests upon cumula- 

 tive evidence, of which this is but one point. Moreover, it is not right to 

 assume that the compass of Columbus showed any easterly compensation, 

 for the custom was to correct the compass before sailing to the true north 

 of each country, as explained by Champlain in Appendix A of my first 

 paper. 



While adhering to the general conclusions of my first paper, and 

 without going over Mr. Harrisse's calculations, which the measure- 

 ment on the map demonstrates to be wrong, I would repeat that 



