EXAMPLE. Thus, suppose the bottom of the vernier cuts the 

 fixed scale between 30.050 and 30.100, the first quantity would be 

 30.050. Then suppose the vernier reading is 28. Add 28 to 30.050, 

 and the sum 30.078, will be the barometer reading. 



READING THE THERMOMETERS. These must always be read in 

 degrees and tenths. Thus, suppose the mercury is just half-way 

 between 72 and 73, the temperature must be entered at 72.5. If not 

 quite quarter way call it 72.2. If nearly 73 call it 72.8, etc. A little 

 practice will soon make this easy. If the mercury is just opposite a 

 whole degree always enter .o ; thus 72.0, 73.0, not 72, 73. 



The minimum or spirit thermometer has a small black " index." 

 The end of this index farthest from the bulb is to be read and 

 recorded as the minimum. 



SETTING THE THERMOMETERS. The dry bulb need never be 

 touched. The wet bulb need be taken down only when the muslin 

 is changed ; but the maximum and minimum must be set once a day. 

 At 9 a.m. the observer will notice that there is generally a break in 

 the mercury column of the maximum thermometer just above the 

 bulb. He must now lift the thermometer carefully out of the bracket 

 and holding it vertically with the bulb end downwards, gently shake 

 it until the mercury quite, or very nearly, unites ; then carefully re- 

 place it. This is called setting the maximum. 



CAUTION. Never let the bulb end of a maximum thermometer 

 be raised higher than the other end, even by half an inch. 



In setting the minimum thermometer at 3 p.m., take the instru- 

 ment off the bracket and gently raise the bulb end until the black 

 index has run down to the end of the spirit ; then replace it care- 

 fully. 



N.B. In setting the maximum or minimum do not remove 

 the thermometer into the sunlight. There is plenty of room inside 

 the box. 



ACCIDENTS TO INSTRUMENTS. The minimum thermometer is 

 liable to have its column of spirit broken, but this can generally be 

 immediately rectified. (A new minimum sent by rail or boat will 

 almost always have this fault, and it must be attended to before 

 mounting). Grasp the thermometer firmly at the end (not the bulb 

 end) and extend the arm horizontally in front of the body. Then, 

 taking care that there is nothing in the way, swing the arm rapidly 

 downwards past the hips. Keep repeating this operation until the 

 column re-unites. The " index " will now be found in the bulb, ancl 

 perhaps stuck fast, but if the thermometer be held bulb upwards a 

 slight tap will release the index. Always make a note of any such 

 occurrence in the field book and on the monthly return. 



UNUSUAL METEOROLOGICAL PHENOMENA. Whenever an un- 

 usual phenomenon occurs, such as a violent storm or a rapid fall of 

 the barometer, take frequent readings of the barometer and direction 



