594 SEC. 14. METEOROLOGY. 



receiver into a train of drying tubes ; the current of air being produced by 

 an aspirator containing oil. By means of this apparatus various soils, &c. 

 can be brought under similar conditions of temperature, &c., and the eva- 

 porations compared for any temperature. The apparatus was especially 

 designed to determine the proper amount of water which should be dis- 

 charged by the artificial drainage system of the Fen Land. 



2899. Integrator of Sun's Heat. 



Scottish Meteorological Society. 



When the water in the globe expands, some of it passes out at the bent 

 upper tube. The level of the water is kept constant by a supply from the 

 cistern which communicates with the globe by the india-rubber ball which acts 

 as a valve. 



Note. The instrument, which is in principle a weight thermometer, may 

 also be used for ascertaining the mean temperature of the air. Designed by 

 Thomas Stevenson, C.E., E.R.S.E., Honorary Secretary. 



2900. Instrument, designed to ascertain the temperatures at 

 which visible vapour is found. Scottish Meteorological Society. 



Water is heated in the main chamber by a lamp beneath, and its temper- 

 ature is read at the point when vapour appears on one of the pieces of glass 

 which are made to revolve slowly above the open end branch tube, and again 

 read as the water cools, at the instant when condensation ceases to be 

 observed. Designed by Thomas Stevenson, C.E., F.R.S.E., Honorary 

 Secretary. 



2901. Ebermayer's Evaporation Apparatus, for deter- 

 mining the degree of evaporation of different kinds of soil. 



Professor Ebermayer, As chaff enburg. 



The evaporating apparatus and the earth thermometer are described at 

 greater extent in " Die physikalischen Einwirkungen des Waldes auf Luft 

 " und Boden," Von E. Ebermayer, Aschaffenburg, 1873. 



2902. Morgenstern's Atmometer. W. Apel, Gottingen. 



Morgenstern's atmometer differs from every other by its being fo anded on 

 the principles of capillarity and of Mariotte's bottle. 



The evaporating vessel is filled with siliceous sand, below which there 

 may be placed a flat stone. This sand is saturated with water by capillarity; 

 any loss of water by evaporation is at once replaced by a corresponding 

 volume of water from a burette. This burette forms a Mariotte's bottle, 

 the upper part of which is closed against the outer air by means of mercury. 

 A tube, which dips into the sand and enters the burette from below, conducts 

 air into the latter in proportion as water is lost through evaporation. When 

 a large portion of the burette has become filled with air, the danger arises 

 that the air column on expanding, by a possible rise of temperature, would 

 exert a pressure upon the water below it in the burette, and thus lean to an 

 over-saturation of the sand. To prevent this the small globular vessel is 

 provided, which is also connected by a small tube with the burette, and into 

 which the water, pushed on by the expansion of the air column, enters. 

 With progressing evaporation this water returns again into the burette, or 

 can later be drawn into the burette. This globular vessel is further intended 

 for the filling of the burette with water, which purpose is accomplished by 

 fixing an india-rubber tube, dipping into water to the open end, and sucking 

 at the upper end of the pipette. Before the burette is completely filled the 



