Kar dd er fyldt. Dette kalder jeg i det følgende ,.det 
ydre Vand*. Hele Apparatet er gjort af lakeret Jernblik. 
Naar Fordunstningsskaalen er tom, er Stetten c og en Del 
af Bøjen over Vandet, men naar naar man helder Søvand 
156 ; 
water, with which the large cylindrical vessel dd is filled. 
This I shall call in the sequel “the outer water’. The 
whole apparatus is made of japanned sheet-iron. When 
the evaporating dish is empty, the stem ¢ and part of the 
i Skaalen, synker Bojen, og Instrumentet er færdigt til 
Forsøg, naar det ydre Vand har naaet et Merke paa Stet- 
ten. Vandet staar da i Fordunstningsskaalen en Centime- 
ter under den øverste Rand. Idet nu Fordunstningen gaar 
for sig, bliver Vægten af Vandet i Skaalen @ mindre og 
mindre, og hele det flydende Apparat løfter sig. For at 
finde, hvormeget Vand der er fordunstet, helder man af 
en Burette rent Vand i å indtil man ser Merket paa Stet- 
ten i Højde med den omgivende ydre Vandflade. Det for- 
dunstede Vand, der er rent Vand, er da erstattet fra Bu- 
retten, paa hvilken dets Volum kan aflæses. Da Overfla- 
den af å er 225 Kvadratcentimeter, vil en Vandmængde 
åf 22.5 Kubikcentimeter fra Buretten svare til en For- 
dunstningshøjde af 1 Millimeter. 
Dersom Fordunstningsskaalen stod frit over det ydre 
Vand, omgivet af Luften, vilde dens Vand i Regelen an- 
tage en Temperatur adskilligt højere end den større ydre 
Vandmasses i Karret dd, og være underkastet en større 
daglig Temperaturvariation end denne. Bøjen vilde ogsaa, 
i haardt Vejr, være tilbojelig til at slænge Vandet ud af 
Skaalen. Jeg indrettede mig derfor paa følgende Maade: 
Saasnart Instrumentet var paa Merke, blev en Blyring 
med to Haandtag v7 lagt paa Bøjen. Med denne Belast- 
ning blev hele det flydende Apparat sænket saa meget, at 
den indre Vandflade i å stod i samme Højde som den 
ydre Vandflade i dd. Den fordunstende Vandflade i a stod 
nu omgivet af en ligeledes fordunstende Vandflade af samme 
Art, Niveau og Temperatur, analog med en Del af selve 
Havfladen. Ved Forsøgets Afslutning tages Blyringen af, 
1 
D 
buoy are above water; but on pouring sea-water into the 
dish, the buoy sinks, and when the outer water has risen 
to a mark on the stem, the instrument is ready for use. 
The water in the evaporating dish is then one centimetre 
below the upper margin. Now, as evaporation goes on, 
the weight of the water in the disha gradually diminishes, 
and the whole of the floating apparatus rises. In order 
to find how much water has evaporated, fresh water is 
poured from a burette into a till the surface of the outer 
water is on a level with the mark on the stem. The 
evaporated water, which is fresh water, is then restored 
from the graduated burette, on which its volume can be 
read off. The surface of å measuring 225 square cen- 
timetres, 22.5 cubic centimetres of water from the burette 
represent in height 1 millimetre of evaporated sea-water. 
If the evaporating dish were kept free above the 
outer water, surrounded by the air, the water it contains 
would as a rule take a temperature considerably higher 
than that of the greater mass of water in the outer vessel 
dd, and be subject to greater variations of temperature. 
Moreover, in a rough sea the buoy would be more lable 
to throw the water out of the dish. I adopted, therefore, 
the following arrangement: — The instrument being ad- 
justed to the mark, a leaden ring, with two handles 17 
was laid upon the buoy. With this ballast, the whole 
floating apparatus was so much depressed that the surface 
of the inner water in @ was on a level with the surface 
of the outer water in dd. The evaporating surface of the 
water in @ was thus surrounded by an evaporating surtace 
of the same nature. level, and temperature, in every respect 
