Section. III., 1896. [ 37 ] Trans. R. S. C. 



III. — On some Measurements of the Temperature of the River Water, 

 opposite Montreal, made during the Winter with a ^Differential 

 Platinui/t Thermometer. 



By Howard T. Barnes, M.A.Sc, 

 Demonstrator in Physics, McGill Universitj'. 



(Communicated by Prof. H. L. Callendar, M.A., F.R.S.) 



The following series of experiments was undertaken at the suggestion 

 of Mr. John Kennedy, chief engineer of the Harbour Commissioners' 

 Works, Montreal. The purpose was to determine to what extent the 

 temperature of the river water varied from the freezing point during the 

 winter months, and to ascertain ihe relation of these variations to the 

 formation and agglomeration of frazil ice. 



Unfortunately, at the time when the measurements would be of most 

 value. Prof. H, L. Callendar, to whom the suggestion had been made, was 

 occupied with work which reqtiired his close attention, and was therefore 

 unable himself to undertake the investigation. At Prof. Callendar's own 

 wish, however, the writer, who was then just completing an investigation 

 in the McDonald Phybics Building, undertook the work. 



Attempts have been made to carry out this work by means of mercury 

 thermometers, but from the severit}" of the investigation and the necessity 

 of reading the thei'mometer out of the water in an atmosphere cooled 

 down many thousand times greater than the ditferences sought for, the 

 chances for accurate observation are small. ' 



The Harbour Commissioners use an instrument which was designed 

 by Mr. Sproule, the assistant engineer, to measure the rate at which the 

 temj)erature of the river-water falls during the early winter before the 

 surface-ice forms. It consists of a mercury thermometer graduated into 

 tenths of a degree, inclosed in a tin case, so that a quantitj^ of the water to 

 be measured is brought up, and serves as a protection against anj- sudden 

 change in the air. For convenience and accuracy it is evident that an 

 electrical resistance thermometer w^ould be most suitable for measure- 

 ments of this kind and especially for determining the small variations from 

 the freezing point during the winter. In the first place such a thermome- 

 ter can be read from a sheltered position, thus avoiding personal errors; 

 in the second place, the temperature may be estimated without drawing 

 the thermometer from the water ; while, in the third place, the variations 

 are so small as to make readings by the ditference method much more 

 accurate than any direct measurement. Early in February Prof. Cal- 



