48 EEPOKT — 1889. 



should be recorded ; if not, the state of the river as regards flood must be 

 put down from general recollections of its average state ; the terms very 

 low, low, average height, slight flood, flood, heavy flood may be conveniently 

 employed. The direction and force of the wind should be carefully re- 

 corded ; this is very important, especially in work on lakes, estuaries, and 

 the sea. The amount of cloud at the time, and the state of the weather 

 since the last observation, should be put down generally, noting especially 

 the fall of rain, snow, or hail. 



8. Taking the Temperatxire.- — The thermometer is to be drawn carefully 

 out of its case, held by the glass ring at the top, and examined to see that 

 the thread of mercury is in free connection with the bulb. See that the 

 thread runs up vphen the fingers are laid lightly on the bulb, so as to 

 warm it, and that the thread runs down again on withdrawing the fingers. 

 If the thread has got detached from the mercury in the bulb, it may be 

 restored to its position by swinging the tube held at arm's-length by the 

 upper part through a vertical semi-circle downwards ; this may require to 

 be repeated several times. 



Temperature of Air. — Having seen that the thermometer is in order 

 and the bulb perfectly dry, hold it perpendicularly by the upper glass ring 

 exposed to the wind, and, if possible, shaded from the sun, for two 

 minutes ; read it as explained in No. 4, and enter the result under 

 ' Temperature of Air.' 



Temperature of Water. — Slip the thermometergently into the japanned 

 tin case to the ring of which a cord about six feet long should be attached. 

 Let the instrument sink in the water, well clear of the shore or the side 

 of the boat, until only the ring and the upper inch of the case are above 

 water ; keep it in this position, moving it gently about, for two minutes, 

 raise it carefully, so that the water retained in the cup surrounding the 

 thermometer-bulb is not spilled ; hold it by the ring of the tin case, 

 having the top of the mercury-thread on a level with the eye, and read 

 as directed in No. 4, recording the result under ' Temperature of 

 Water.' 



After the observation, withdraw the thermometer, dry it carefully, dry 

 the tin case also, re-insert the thermometer, and hang it up in a safe place 

 out of the sun, and not too near a fire, until required for use again. 



9. The Observation Boole. — The observer's name, station, and the 

 number of his thermometer to be entered on the first page. All the 

 observations should be entered in the book at the time they are taken ; 

 the best memory must not be trusted. Each day the readings should be 

 copied into a spare book, to be kept by the observer. When the original 

 book is filled, it is to be posted to John Guun, Esq., F.R.S.G.S., Royal 

 Scottish Geographical Society, 80a Princes Street, Edinburgh, to whom 

 all communications regarding thermometers or observing books are to be 

 addressed. 



Letters connected with the observations, especially with reference to 

 thermometers, ought to be marked ' Temperatures ' on the envelope. 



10. Accidents to Thermometers. — If a thermometer is broken in transit, 

 or otherwise, it should be immediately returned, together with its case 

 and packing cylinders, and a statement of the way in which the accident 

 happened, to Mr. Gunn, who will forward another as soon as possible, so 

 that the least delay may take place. 



