Forsøg til Bestemmelse af Havvandets 
Fordunstning. 
We Siden af de ovenfor beskrevne meteorologiske lagt- 
tagelser paa Nordhavs-Expeditionen anstillede jeg de i 
det Følgende beskrevne Forsøg til Bestemmelse af Hav- 
vandets Fordunstning. Da Resultatet af disse Forsøg ikke 
viste sig at svare til de Forventninger. jeg havde næret. 
har jeg været 1 Tvivl om, hvorvidt det var værdt at offent- 
liggjøre den følgende Beskrivelse. Denne Tvivl har jeg 
imidlertid ladet fare for den 'Betragtning, at Beskrivelsen 
af Apparaterne og deres Anvendelse muligens kunde tjene 
til Vejledning for fremtidige Forskere, der havde Anled- 
ning til, med forbedrede Apparater og under gunstigere 
Forhold, at yde nye Bidrag til Oplysning om en Natur- 
proces, som det for Meteorologien altid maa være af den 
største Interesse at lære at kjende nøjere. Og hvorvel det 
ikke har lyktes mig at finde Overensstemmelse mellem de 
for Tiden gjældende Formler for Fordunstningen og Resul- 
taterne af mine daglige Maalinger, turde dog enkelte af 
disse indeholde nogle Vink til Belysning af Fordunstnings- 
processen paa Havet. 
Fordunstningsmaaleren var construeret efter min egen 
Tegning, efter Flydevegtens Princip. Fig. 12 viser det 
Apparat, jeg brugte i 1876, og Fig. 13 det, jeg brugte i 
1877 og i 1878, begge i */; af den sande Størrelse. 
12 er b en Boje, der bærer en Stet c, der igjen bærer 
Fordunstningsskaalen a. Denne Skaal har cylindrisk Væg 
og en svagt conisk Bund. Fordunstningsskaalens frie Over- 
flade er 225 Kvadratcentimeter, samme Størrelse som 
Regnmaalerens.  Bøjen b har i sin nedre Ende en Blybal- 
last. Den flyder i Søvand, hvormed det store cylindriske 
I Fig. 
Experiments undertaken to determine 
the Evaporation of Sea-water. 
part from the meteorological observations taken on the 
North-Atlantic Expedition, and set forth in the foregoing 
pages of this Memoir, I made experiments — described in the 
sequel — to determine the evaporation of sea-water. Mean- 
while, the result of these experiments not havmg answered 
to expectation, I felt some doubt at first as regards the 
propriety of publishing the following account. This doubt, 
however, has given way to the justifiable consideration, 
that a detailed description of the apparatus and the mode 
of usmg them, may possibly prove of value to future ob- 
servers, who, provided with improved apparatus and under 
more favourable circumstances, would have opportunity of 
contributing new data towards the elucidation of a natural 
process with regard to which the meteorologist must always 
feel the greatest interest in gaining a more intimate acquain- 
tance. And though I have not succeeded in showing 
agreement between the formule for evaporation at present 
accepted and the results of my daily measurements, some 
few of the latter may perchance prove suggestive in throwing 
further light on the process of evaporation at the surface 
of the ocean. 
The atmometer was constructed after my own design, 
on the same principle as the hydrometer. 
sents the apparatus used in 1876, and Fig. 13 that used 
in 1877 and in 1878, both on a scale one-fifth of the 
In Fig. 12, b is a buoy bearmg a stem c, 
Fig. 12 repre- 
actual size. 
which in turn supports the evaporating dish a. This vessel 
has cylindrical walls and a slightly conical bottom. The 
free surface of the evaporating dish measures 225 square 
centimetres, the same as that of the rain-gauge. ‘The buoy 
b is ballasted at its lower end with lead. It floats in sea- 
