XXX ROYAL SOCIETY OF CANADA 
last season (1900) afford the information required. To obtain further 
simultaneous comparisons where the currents are strongest, arrange- 
ments were also made for observation of the turn of the current at 
L’Islet, and in the Upper and Lower Traverse. 
The two permanent tidal stations in the St. Lawrence region, are 
at Quebec itself, and at Father Point, 180 miles below; and the chief 
object of the observations at other places in this region, was to obtain 
“tidal differences” by which the time of the tide may be correctly com- 
puted for them. The places selected-as most important for this object, 
were Grosse Isle, L’Islet, Orignaux Point, Riviere du Loup, Tadousac, 
and Cape Chatte; this last being opposite Point .de Monts, which may 
be considered as the true mouth of estuary of the St. Lawrence. It will 
not be necessary to describe the installation of the tide-gauges, and the 
methods adopted to secure accuracy, and especially, correct time for the 
observations; which, for the purpose in view, is of the first importance. 
The observations obtained have made it evident that the tide and 
current from the Traverse downward to the mouth of the estuary, can 
be referred more correctly to Father Point than to Quebec. Father 
Point is about half-way up the open estuary, at only seven -miles from 
the 100-fathom line in the offing; and the deep water of the estuary 
extends up as far as Orignaux Point, or the Traverse. Quebec, on the 
other hand, is in reality in the river, above the true-head of the estuary, 
which must properly be considered as being below Orleans Island. It 
is there -also that the tide has its maximum range; which corroborates 
this view. 
The time taken by individual tides in running up the.estuary from 
Father Point to Quebec, varies widely during the course of the month, 
from its mean value. It appears probable that this variation occurs 
chiefly in the upper part of the run of the tide, towards Quebec. 
An investigation was accordingly made to ascertain in what way 
tide tables for Father Point could be correctly computed from Quebec. 
After considerable research, it was found that this could be satisfac- 
torily done by the use of a double series of variable differences in time; 
one series varying with the moon’s phases in the period of the synodic 
month, and the other varying with the moon’s distance in the period of 
the anomalistic month. The variations, which are greatest in the case 
of low water, amount to 32 minutes and 25 minutes respectively. The 
total or extreme variation amounts to the sum of these two. These 
values are derived from a digest of two complete years of simultaneous 
observations at Father Point and Quebec, which afford differences for 
1280 individual tides. 
Tide tables for Father Point will be published for next year, which 
have been calculated by means of this double series of variable differ- 
