24 



THE GAKDENEK'S ASSISTANT. 



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into the ground to the required depth. Into 

 this tube a thermometer is lowered, and the top 

 closed by means of a copper cap. An open 

 position on a lawn should be chosen for this 

 instrument. The "best depth q 



is one foot. The thermo- 

 meter should be drawn up 

 when an observation is 

 taken, and read to the near- 

 est degree. The reading 

 should be entered to the 

 same day as that on which 

 it is made. 



Bain-gauge. — The most 

 useful form of rain-gauge 

 for a garden is one made of 

 galvanized iron. It has a 

 deep rim, and is 5 inches in 

 diameter. 1 An open posi- 

 tion on a lawn should be 

 selected for it, away from 

 trees, walls, or buildings — 

 at the very least as many 

 feet from their base as they 

 are in height. It should be 

 secured in position by four 

 stakes firmly driven into 

 the ground round it, as 

 shown in fig. 7. The top of 

 the rim should be one foot 

 above the ground, and must 

 be quite level. Each morn- 

 ing the gauge should be examined, whether any 

 rain be known to have fallen or not. If any 

 water be found in the receiving bottle or can, it 

 should be emptied into the glass measure sup- 

 plied with the gauge. When a reading is taken 

 the measure should be quite vertical, and the 

 nearest division to the height of the water in it 

 noted, and the amount entered in the observation 

 book to the previous day, and not to the day on 

 which the measurement is made. Each of the 

 short divisions represent *01 inch (or a hundredth 

 of an inch), the longer divisions "05 inch (or five 

 hundredths of an inch), and the long divisions 

 having figures attached -10 (or tenths of an inch). 

 For instance, the amount indicated in the mea- 

 sure shown in fig. 8 would be two tenths of 

 an inch (or -20 inch). As the glass measure is 

 graduated to hold only half an inch (or -50 

 inch), in order to measure a heavy fall of rain 

 two or more readings will have to be taken. 

 Say, for example, if the first measurement made 

 be -46 inch, the second 43 inch, and the third 



i This gauge is made by Negretti & Zambra, Holborn Viaduct, 

 London, and its price, with measure, 12s. 6d. 



•28 inch, the three should be added together and 

 the entry made as 1-17 inch (or one inch, one 

 tenth, and seven hundredths of an inch). 2 



In times of snow, measure off in the glass 

 measure sufficient warm water to melt the snow 

 collected in the funnel of the gauge. Make a 



Fig. 6.— Symons's Earth 

 Thermometer. 



Fig. 7.— Rain-gauge (Snowdon pattern). 



note of the measured quantity of warm water, 

 and then pour it upon the snow in the funnel. 

 Next measure the water found in the receiving 

 vessel, and afterwards deduct from this measure- 

 ment the quantity of warm water which had 

 been added to melt the snow. For example, 

 suppose the warm water to have measured 45 

 inch, and the water, including 

 the melted snow, found in the 

 receiver -76 inch, then the entry 

 made in the observation book 

 should be -76 inch less °45 inch 

 (or *31 inch). In a deep fall of 

 snow, where the funnel is not 

 large enough to hold the quantity 

 deposited, measure with a rule 

 the average depth of the snow 

 on the ground, and take one- 

 twelfth as the equivalent of water 

 which it would yield when melted. 

 For instance, suppose the rule 

 measurement to be 10 inches or 10 - inches, 

 divided by 12 this would give *83 inch as the 

 amount to be entered in the observation book. 

 This latter plan, however, should not be 



2 Application should be made to Mr. G. J. Symons, F.R.S., 62 

 Camden Square, London, N.W., for his "Arrangements for the 

 Systematic Observation and Record of the Rainfall of the British 

 Isles", which will be sent free of charge. 



Fig. 8.— Rain- 

 gauge Measure. 



