[BARNES] TEMPERATURE OF RIVER WATER 4t 



increase in the amount of fra/il was noticed. This was found cliiin-ini;' to- 

 the compo-tube leadinc; to the thermometer. 



From Mai'ch 6th to 10th there was warmer weather, to be followed 

 on March 11th by another cold dip, — 8° F. This also had a slii^ht effect 

 on the water sending- it down from + -0005° C. to _-0039° C. 



From March 12tli to 16th tlie air-temperature remained fairly uni- 

 form, rising during the day to about + 20° F. and sinking during the 

 night to a few degrees either way from 0° F. The river temperature 

 showed but slight variations from the freezing point. 



During the milder weather, and in general, the river from six to 

 eight feet below the surface ice was warmer than that at a depth of two 

 feet, although by only one or two thousandths of a degree. 



General Considerations, with Eeference to the Formation of 

 Frazil and Anchor-ice. 



The extreme steadiness of the temperature of the water during the 

 time of the investigation is a matter of great interest. Even when the 

 atmosphere was some 60° F. below freezing, the river did not differ 

 throughout its depth by as much as one hundredth of a degree from 0° C. 

 In open stretches of water, Avhere the river is not protected by a badly 

 conducting layer of surface ice, it is not likely that any great variations 

 occur. Should differences of several degrees exist, as some observers have 

 found, it would not be without effect on the currents under the ige. it 

 is true, that under the most favourable laboratory conditions, water, 

 which was kept pei-fectly quiet, and free from dissolved air, has been 

 cooled to several degrees below freezing, but this is a condition hardly 

 comparable with a swiftly running river full of fine particles of deuudated - 

 material, and free to absorb air along its immense surface. 



A simple and effective experiment was carried out at McGill Uni- 

 versity liy Prof. Nicolson, which Avill have considerable bearing on the 

 question of the formation of frazil. A quantity of water in a tub was kept 

 in rapid motion under the influence of a cold atmosphere in winter. The 

 result was that fine needle crystals of ice, in every respect similar to ■ 

 frazil, were formed throughout its mass until the whole became some- 

 what like a thin paste. During the pi'Ogress of the experiment no devi- 

 ation in the temperature of the water from freezing could be detected 

 with a thermometer reading to hundredths of a degree. 



Mr. Keefer, former president of the Canadian Society of Civil 

 Engineers, in the discussion following Mr. G. H. Henshaw's paper on 

 Frazil, published in the Transactions of that society for March, 1887, 

 gives an observation made by himself, which accords well with Prof. 

 Nicolson"8 experiments. He has noticed, that while crossing the St. 

 Lawrence Eiver, opposite Montreal, in a canoe, when the thermometer was 



Sec. III., 1896. 4. 



