[murphy] the ice question 167 



along, however, almost as regularly as winter during some 20 years of 

 my experience. Shut-downs by frazil constituted 85 per cent of all the 

 slmt-downs during this long period and, it often happened that the 

 operators of neighbouring industrial power plants had the satisfaction of 

 getting their works started next morning with the aid of nature's remedy 

 — the heat of the sun — just as soon as the others who had laboured all 

 night. 



It has long been generally recognized that the rising sun brings 

 almost immediate relief to a plant frozen up with frazil. This was per- 

 haps the first lesson in regard to relief from ice troubles that came to my 

 attention. It was well known that before any appreciable rise in water 

 temperature occurred, in the morning, water-wheels that had been com- 

 pletely shut down for hours immediately started running again. 



The second lesson that I learned in connection with the frazil ques- 

 tion was in regard to the necessity of keeping the vulnerable parts of 

 water power apparatus protected from the action of the cold air. 



For a number of years I noted the operation, and the annual shut- 

 ting down, of a great number of plants, and I early became convinced 

 that water wheels protected by wooden racks were better able to with- 

 stand frazil attacks than those protected by iron racks. This conviction 

 — " theory " some called it — was confirmed as time went on ; it was 

 often supported by actual occurrences. In addition to these observations, 

 I frequently encouragingly joined the beaten ice rakers — but only for 

 brief periods at a time, because raking ice in the path of a blizzard 

 is not an attractive occupation. With rake in hand I found that frazil 

 could be removed from w^ooden racks very much as plastic mud can 

 be scraped from one's boots, but, that it requires much more physical 

 effort to detach frazil from a metal rack. Frazil actually crystallizes 

 on a metal rack. ^ 



"Why these different conditions in regard to iron and wooden racks 

 obtain will be better appreciated by another glance at Fig. 3. As may 

 be noted, a large area of iron rack projects into the air. When frazil is 

 being formed the temperature of the air is frequently down to 0° F. — 

 sometimes to — 20° F. When frazil is being formed Dr. Howard T. 

 Barnes has shown that the water's temperature actually goes a few 

 thousandths of a degree below the freezing point. A note of the tem- 

 peratures of the air and the water has been made upon this drawing, Fig. 

 3, so that they will be better impressed upon the mind. Assuming that 

 the air temperature during a frazil attack is down below zero (0° F.) and 

 that the water is just at 32° F. — at the freezing point. Is not this a pic- 

 ture of an ideal ice-manufacturing arrangement ? Here is water just at 

 the freezing point — perhaps a thousandth of a degree below it — just ready 



