40 ROYAL SOCIETY OF CANADA 



mentSAvitli its foiiiKlation on the solid earth of the pier. This eftectuaily 

 prevented vilu-ations from disturliing the galvanometer readings. 



Method of Observation. 



The method of measurement consisted in keeping the short end of 

 the thermometer immersed in a carefully prepared mixture of snow and 

 water in a large puncheon inside the shanty and determining how much 

 the end in the river differed from this. 



A zero reading was obtained from time to time by immersing the 

 river end in the puncheon with the shorter end. 



Knowing that the temperature of a co-existent mass of ice and water 

 is exactly 0° C. or 32° F. and practically independent of external con- 

 ditions, it is possible to give the temperature of the river at any time by 

 determining the amount of difference on the bridge-wire from the zero 

 reading, when the longer end was in the river. 



]iESULTS OF THE OBSERVATIONS. 



During the complete series of experiments no difference of as much 

 as a hundredth of a degree from freezing has been recorded. 



From February 15th to 17th, the greatest variation in river temper- 

 ature took place, when the air sunk from 0° F. to — 28° F. It is possible 

 to limit this within one hundredth of a degree. During this time a large 

 amcnint of frazil was found accumulated under the surface ice. 



During February 18th, no reading of any value could be obtained, 

 owing to the giving out of the soldered join already mentioned. The 

 entire day of F''ebruary 19th was employed in renewing one of the ends 

 of the thermometei'. 



During milder weather, from Februaiy 20th to 22nd, the water 

 remained almost steadily at the freezing point. Careful reading gives a 

 difference from the freezing point of -f -0015° C. From February 23rd 

 to 2-lth the air did not sink below + 10° F , while the highest it attained 

 was + 35° F. During this time there was some rain. The river did not 

 show any greater variation from the freezing point, but a decrease in the 

 amount of frazil was noticed. 



From February 25th to 27th. a cold dip of —10° F. caused the river 

 to sink slightly below the freezing ])oint. Observation gives — -005° C. 

 During the time from February 28th to March 3i'd, the temperature of 

 the air varied from + 42° F. to + 16° F., never sinking below the latter 

 point. The river remained at the freezing point with variations slightly 

 above. 



On March 4th the air tempei-ature went suddenly down to zero. This 

 had the effect of lowering the river temperature 0057° C. below freezing. 

 On the following day the under-cooling was only -0004° C, while an 



