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 observation, 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 



