THE REY. W. WHEWELL’S RESEARCHES ON THE TIDES. 
167 
and analysed ; the knowledge that the case does thus deserve further inquiry, we owe 
to the very great exactness and perseverance with which the observations were made 
by Admiral Lutke in 1827 and 1828. 
2. Port of Novo- Arkhangelsk, Isle of Sitkhce, Norfolk Sound, on the north-west 
coast of America, latitude 5 7° 2' N., longitude 135° 18' west of Greenwich. Obser- 
vations made in July 1827*. 
The Isle of Sitkhce is nearly in the same latitude as Kamtchatka, on the opposite 
side of the Northern Pacific, the distance of the two coasts being in that part about 
66 degrees of longitude. The differences which have been found to prevail in the phe- 
nomena of the tides even in places almost adjacent, leave us without any good ground 
of expectation that the tides of these two coasts will be found to resemble each other, 
even in their general features. It is found, however, that some of the most curious 
of the circumstances which mark the Petropaulofsk tides, appear also in those of 
Novo-Arkhangelsk . 
The Sitkhce tides exhibit a very great diurnal inequality both in the heights and 
in the times. The amount of this inequality at high water reaches an hour (half an 
hour positive and negative) ; at low water it is somewhat less. The diurnal inequality 
of the height of high water is two feet and a half ; at low water its maximum effect 
amounted to five feet, the greatest rise from low water to high water being about 
fifteen feet. 
Thus we see that at Sitkhce, as in Kamtchatka, there is a very large diurnal in- 
equality Avhich affects the time of high water more, and the height less, than those of 
low water. The motion of the surface will be in its general features the same in this 
as in the former case, although it does not appear, so far as the observations before 
us can show, that one of the two semidiurnal tides is ever obliterated. 
I may add, that it appears also, so far as we can judge from a short series of ob- 
servations, (a month, with interruptions,) that the maximum and zero of the high- 
water diurnal inequalities alternate with those of low water, which we have already 
noticed as so perplexing a circumstance at Petropaulofsk. 
The diurnal inequality being allowed for, we obtain a semimenstrual inequality of 
the mean tide at Sitkhce, which is tolerably regular. According to our discussion, 
the greatest and least lunitidal intervals are 12 h 10 m , and 13 h 25 m from the lunar 
transit of the preceding half-day ; the mean on the corrected establishment being 
12 h 49 m , and the total amount of the semimenstrual inequality 75™. 
Under these circumstances we cannot doubt that the tides of Kamtchatka and 
Sitkhoe are to be explained in the same way, whatever the explanation may be ; and 
probably the same features extend in some measure over the whole of the North 
Pacific. 
* Some additional observations were made in 1832 and 1833, but too interruptedly to be of much service in 
these discussions. 
