272 
THE PHYSICAL GEOGRAPHY OF THE SEA. 
of country, to every planter, and upon all cultivated fields, depend 
the fruitfulness of this country, the sterility of that. 
The principal maritime nations, therefore, have done well by 
agreeing to unite upon one plan of o!)servation, and to co-operate 
with their ships upon the high seas with the view of finding out 
all that patient research, systematic, laborious investigation, may 
reveal to us concerning the winds and the waves ; and philosoph- 
ical travelers, and every sailor that has a ship under his foot, may 
do even better by joining in this system. 
584. By the recommendations of the Brussels Conference, ev- 
ery one who uses the sea is commanded or invited to make cer- 
tain observations ; or, in other words, to propound certain queries 
to Nature, and to give us a faithful statement of the replies she 
may make. 
Now, unless we have accurate instruments, instruments that 
will themselves tell the truth, it is evident that we can not get at 
the real meaning of the answers that Nature may give us. 
An incorrect observation is not only useless of itself, but, when 
it passes undetected among others that are correct, it becomes 
worse than useless ; nay, it is mischievous there, for it vitiates 
results that are accurate, places before us wrong premises, and 
thus renders the good of no value. 
585. Those ship-masters who, entering this field as fellow-la- 
borers, will co-operate in the mode and manner recommended by 
the Brussels Conference, and keep, voyage after voyage, and as 
long as required, a journal of observations and results according to 
a prescribed form — and which form is annexed, under the title of 
Abstract Log — are entitled, by sending the same, at the end of 
the voyage, to the Superintendent of the National Observatory, to 
a copy of my Sailing Directions, and such sheets of the Charts as 
relate to the cruising-ground of the co-operator. 
586. There are two forms of abstract logs : one, the more elab- 
orate, for men-of-war ; the other for merchantmen. The observa- 
tions called for by the latter are a minimum, the least which will 
entitle the co-operator to claim the proffered bounty. It must 
give, at least, the latitude and longitude of the ship daily ; the 
height of the barometer, and the readings of both the air and the 
water thermometer, at least once a day ; the direction and force 
of the wind three times a day — first, middle, and latter part — at the 
