1819.]} in the Endeavour River. 205 
The moon’s declination will materially affect the height of the 
tides. The waters do not rise equally throughout the whole 
circumference of the same meridian, but they are highest in those 
parts in which the moon passes the zenith or the nadir, and 
lowest at 90° from these two points. Hence in the southern 
hemisphere, when the moon’s declination is south, the spring 
tides will be greatest, which accompany her passage of the 
meridian ; and these will be by night at the full, and by day at 
the change of the moon. On the contrary, when the moon’s 
declination is north, the spring tides will be greatest; in the 
southern hemisphere, when they follow about 12 hours after the 
passage, and these will then be by day at the full, and by night 
at the time of the new moons. The same might be applied, 
mutatis mutandis, to the northern hemisphere ; but. it it unne- 
cessary to enter into this part of the detail, as the ship struck in 
about 15° of south latitude. Now from the Nautical Almanac 
for 1770, we shall find the following data: 
New Moon, June 22, with declination....... 21 NM 
PilleMogon; July 7 Seaye! PIV OL ee 19S. 
New Moon, July 22 ......... Oe SE S FLT AN: 
Hence it would appear, at first sight, that the moon’s declina- 
tion would at once explain the phenomena; but still the difficulty 
is not removed; for a more particular attention to the paper 
will show, that it was what is here considered as the day tide, 
which was observed to rise highest, and not the night tide, as a 
less attentive perusal of the account would probably lead us to 
imagine. 
We know that in the open ocean, the highest spring tides, at 
the times of the new and full moon, are in the morning and 
afternoon about 3 and 15 hours after the moon’s passage of the 
meridian ; and though this time hardly suits any other situation, 
still all the causes which tend to affect the time, act by retard- 
ing, and never by accelerating the event. Now Capt. Cook 
expressly tells us, that at the full and change of the moon, it was 
high water in the Endeavour river about a quarter after nine; 
the high tide in the evening must, therefore, have been that 
which in the open seas had occurred after noon, and which did 
not arrive at its height in the river till several hours after it 
would have been high water there, if the moon’s attraction 
could have acted freely and without impediment. This retarda- 
tion could not be occasioned by the situation which had been 
chosen in the river, since that was not far from its mouth; 
neither do the New Hebrides and other islands, which lie to the 
east of New Holland, appeer to form a barrier which could 
stop the swell of the whole southern ocean for so long a time. 
The cause, therefore, must be looked for in some other circum- 
stances, and these seem to be the want of a passage for. the 
waters to run off. The east coast of New Holland extends 26° 
7 
