[MURPHY] THE ICE QUESTION IS I 



power plants, this practice was not iiniversall}'' adopted as a positive or 

 reliable preventive of frazil troubles. It was sometimes harder to re- 

 move the cedar boughs from the racks than the frazil. 



Seeing Avater works, electric light and railway systems annually shut 

 down by frazil for many years and being very much interested in their 

 continuous operation, I made many attempts to ascertain just when frazil 

 attacks might be expected. I obtained data from the meteorological 

 bureau at Toronto in regard to barometer and thermometer readings, as 

 well as records of the direction and velocity of the w^ind, and such other 

 atmospheric conditions as might have any bearing upon the subject of 

 frazil formation. A review of these data, when tabulated, showed that 

 frazil attacks occurred on some occasions when the temperature of the 

 air was only 4 or 5 degrees below the freezing point and at other times 

 when the temperature was 30 or 40 degrees below the freezing 

 point. Severe cold alone did not seem to cause frazil to form. 

 Besides showing great air temperature variations these data also 

 showed that frazil attacks were invariably accompanied by a northwest 

 wind. This last point was the only one, so far as we could see, which 

 seemed to have any material or direct bearing upon the frazil question. 

 We then turned our efforts to the task of recording, several times daily, 

 the temperature of the water itself, and from this work we at last be- 

 come able to foretell to a certainty, a few hours ahead, when frazil would 

 arrive. We found that as soon as the temperature of the water was 

 lowered to within one degree of the freezing point " trouble " was at 

 hand, and we also found that the time of the lowering of the water's 

 temperature to the freezing point was the time when frazil was made if 

 a northwest wind was blowing. Fig. 2a illustrates this point. 



Fig. 2a shows how gradually the temperature of the water reaches 

 the freezing point— 32° Fahr.— after many days oJ^cold weather, and 

 that it remains just at the freezing point until warm w^eather sets in. 

 Frazil is formed at the time the temperature of the water falls to 32° 

 Fahr. — in this instance on Dec. 3rd. 



We found, further, that the temperature of the water in the 

 river remained exactly at the freezing point during all the rest of the 

 winter. An exception to this rule sometimes occurred when an early 

 cold spell in November was succeeded by mild weather ; under the latter 

 condition the water's temperature was raised a degree or two and when 

 this happened another attack of frazil was to be expected when cold 

 weather set in again. Our water temperature measurements were made 

 with a mercury thermometer, and I wish to empliasize this point in order 

 to explain what may otherwise look like a discrepancy between the results 



