THE TIDES OF THE BAY OF FUNDY—MURPHY. 61 
water referred to datum, which is from 47 to 50 feet below 
low water Spring tides.* 
BAlE VERTE 
Half tide or mean level of sea 1870 and ’71, from August 
till May 10th was about 71.54. So that the mean level of sea at 
half tide is just 10 inches higher at Baie Verte than at Cum- 
berland Basin. 
It is also well worthy of remark that the Bay of Fundy 
tides seldom rise to a greater height above the main level of the 
sea than 22 feet; and the great Saxby tide did not rise to a 
greater height above the same level than 29 feet. ; 
The tidal wave, then, on its retreat scoops back with it 
just as much water in depth, below the mean level of the sea, 
as it carries in with it in its advance above the level. 
It would be a great error then, to say that the tides rise in 
the Bay of Fundy above the level of the sea fifty or sixty feet, 
because they do not rise more than about half that height above 
sea level. But it would be correct to say, between the level of 
lowest and highest water, there is a difference of level of from 
50 to 60 feet. 
The oscillations of the tidal vertex, or daily elevation of 
high tide above datum, between tides occurring at full and new 
moon, and those occurring at the moon’s quarters, in the Bay of 
Fundy, are not, relatively considered, proportional to the differ- 
ence between the respective heights of springs and neaps in 
places where those abnormal tides do not occur. The minimum 
level that was reached by neaps during high tide was about 85 
feet above datum, whilst the height of springs seemed to turn 
about 94, having a difference only of about 9 feet, or say as 9 to 
8. The universal law of gravitation when the sun and moon are 
acting in conjunction, as at the full moon, and when the 
moon is acting alone, as at the quarters, would be as 9 to 
5 nearly. Thus the translating, impinging or crowding 
* Care must be taken not to confuse the heights given in the above datum with the height 
above low water. For the convenience of levelling or obtaining levels of surface, the Engineer 
invariably computes all heights from an arbitrary level taken well down below the lowest point of 
surface which he calls datz7z, so as to avoid minus quantities in computation. The heights given 
here are about 50 feet below low water. The height, therefore, above low water for main level of 
sea will be 20,71 feet. 
