370 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



2° *8 7, showing a difference of eight degrees in favour of 

 the winter of 1857-58. The temperatures recorded 

 were as foUows : — 



1855-56. 1857-58. 

 December .... -8-31 . . -9-11 

 January .... —10-55 . . —6-2 

 February .... -1-71 . . -6-68 



Winter Mean . . . —6-85 . . -2-87 



The thermometers supplied to the Eed Eiver Expedition 

 in 1857, were made by Negretti and Zambra, and were 

 of the best construction.* They had been compared with 

 a standard at the Provincial Observatory, and their errors 

 recorded, but it does not appear that the proper correc- 

 tions were made after each observation. Mr. Gunn's 

 thermometer was an ordinary instrument, and, like many 

 of its class, liable to errors at low temperatures. It is, 

 therefore, probable that his winter temperatures are too 

 low, and that the true mean of the winter months at Eed 

 Eiver, and consequently the annual mean, may be con- 

 siderably higher than it appears from his observations. 



The cold of February 1858 was exceptional. At 

 Montreal it was the coldest February on record, being 

 14° -05 below the mean temperature of February, 1857.f 

 But it cannot be denied that the winter cold of Eed 

 Eiver is excessive, and the temperature sometimes falls so. 

 low as to freeze mercury in a few minutes. 



The meteorological register kept at the Stone Fort, 



* These thermometers, together with other meteorological apparatus, 

 were furnished to the different members of the Red River Expedition in 

 1857, by the permission of the Rev. Dr. Ryerson, Chief Superintendent of 

 Schools, from the stock of instruments provided by the Chief Superintendent 

 for observatories attached to the Grammar Schools throughout the Pro- 

 vince. The thermometers were compared and their errors determined and 

 tabulated at the Provincial Observatory. A table of errors was attached to 

 each instrument. 



f Records of St. Martin's Observatory, Isle Jesus. 



