L. CASELLA'S CATALOGUE 



FIG. 72. 



70. Evaporating Dish or Gauge; of copper, with wirework edge for protection from 



birds, etc. The receiving surface of same diameter as the gauge with which 

 it is used, say five inches, with graduated glass measure . 15 6 



71. EVAPORATING GAUGE, as above, eight inches diameter inside . 140 

 Instructions for Evaporating Gauge. Nearly fill it with water, measured by the graduated 



glass measure, and place it out-of-doors freely exposed to the air. After exposure, again 

 measure the water, and the difference between the first and second measurement shows the 

 amount that has evaporated. Should rain have fallen, however, during the interval, the 

 quantity equal to that collected in the adjoining rain gauge must first be deducted from the 

 evaporator, the remainder, compared with the measured quantity put in, shows the amount 

 that has evaporated. For districts which are subject to very heavy rainfall, an evaporating 

 gauge, with overflow pipe to meet any exigency, may be had at a slight increase in the price. 



72. SELF-RECORDING EVAPORIMETER OR TIDE GAUGE (fig. 72) shows the general 



design of this new and interesting instrument. It answers equally well for a 

 rain gauge as for either of the above-named purposes, or for the rise and fall 

 of water in a river, canal, lock, or any other body of water, the rate of evapora- 

 tion, etc., showing the exact time at which any increase or reduction may have 

 occurred . . .. . . . . 32 



DESCRIPTION a is a 30-hour timepiece of best English make ; b the carriage carrying the 

 pencil which marks the paper on the cylinder g ; c pulley over which the cord runs to com- 

 municate with the float-wheel d ; e small wheel communicating with d, from which the line is 

 connected with the float resting on the water. The paper is changed every 24 hours. The angles 

 of pulleys, etc., may be altered to adapt it for almost any position. 



73. Rain (iailgC; improved self-registering, receiving surface 100 inches diameter, 10 



inches square. In this arrangement the rain is measured to tenths and 

 hundredths of inches, and a continuous record is kept to the depth of 100 

 inches of the quantity of rain faUen (fig. 73) p. 23 . 4 10 



The registering parts are all of copper, carefully tinned, and the arrangement so simple 

 that any one can clean the works when needed, or adjust the gauge to the greatest nicety ; 

 indeed, this adjustment is so simple that it may be as well for the purchaser to test it on 

 receiving it, or at any time after its removal; thus the small measure, when quite full, 

 holds five cubic inches of water ; this quantity passed through the instrument should move 

 the hand of the hundredth circle five divisions, or half-way round, and is equivalent to half 

 a tenth of an inch in depth of rain ; and the receiving trough being ten inches square 

 at the top or=100 superficial inches, five cubic inches equals one -twentieth, or half a tenth of 

 an inch 0.05. 



