242 On the Bain and Drainage - Waters at Rothamsted. 
and Evaporation from uncroppetl land. The Third Part will 
deal with the Drainage-waters from land cropped and manured. 
In the Fourth Part we shall endeavour to apply some of the 
facts previously given to the elucidation of certain agricultural 
problems. In each section of the subject we hope to find space 
for a brief glance at some of the results obtained by others in 
the same field of inquiry. 
.Part I. — The Amount and Composition of the Rainfall. 
1. The Rain-gauges. — With the purpose of determining ac- 
curately the amount of the rainfall, and at the same time of 
collecting rain in sufficient quantity to allow of its chemical 
analy sis, a large Rain-gauge was erected during the winter of 
1852-3 in one of the arable fields on the farm at Rothamsted. 
The collecting funnel was of wood lined with lead. Its form 
was rectangular ; the length 7 feet 3-12 inches, the width 6 feet. 
It had therefore an area of of an acre. The surface of the 
funnel was 2 feet above the level of the surrounding ground, 
and 420 feet above the level of the sea. 
The water collected in this funnel was received by a glass 
carboy standing beneath it. This carboy when nearly full over- 
flowed through a pipe in the neck into a second carboy in 
connection with it. The quantity of water collected was, when 
necessary, ascertained twice a day by weighing the carboys. One 
inch of rain falling on this gauge would furnish 226 J lbs. of water. 
This gauge was in constant use from February 1853 to 
November 1876. Latterly, that is since August 1873, the use 
of carboys was discontinued, the water being received in gal- 
vanised iron cylinders fitted with gauge-tubes, and its quantity 
determined by measurement instead of by weight. 
The large gauge just described has now been replaced by 
another of identical form and area, erected in the immediate 
neighbourhood of the old gauge. The land on three sides of 
the new gauge is not now under tillage, having been laid down 
in grass in 1874. On the remaining side is a field continuously 
cropped with roots. The edge of the collecting funnel of the 
new gauge is constructed of plate-glass, the remainder of the 
gauge being, as before, of lead. The edge of the funnel is 
about 1 foot above the level of the surrounding soil. 
The water from the new gauge is received in a galvanised 
iron cylinder placed beneath ; this when nearly full overflows 
into a similar cylinder standing at its side, which in its turn 
overflows into a third, and that into a fourth. Each cylinder 
will contain rather more than half an inch of rainfall, and is 
provided with a graduated gauge-tube by means of which the 
