From the continuous records of slack and strain combined with the weight of the cable it is a simple matter to calculate and plot the depths along the whole route of the cable as actually laid. The graph, compiled from the actual records obtained during the laying of the Canso-Fayal section of the Commercial Cable Company's system, shows by the full line the actual strain recorded which secured the even distribution of 8 per cent. of slack, and by the dotted line the strain that would have been applied if the soundings taken during the preliminary survey had been the only source available, although the conditions of sea and weather favoured close adherence to the proposed route. The ordinates of the curve give the strain in cwts., and the abscissae the distance in miles measured from the Canso end; as the strain is proportional to the depth, 18 cwts. corresponding to 1000 fathoms, the black line represents to an exaggerated scale the contour of the sea bed.