ON THE SEASONAL VARIATIONS OF TEMPERATURE. 487 



the wind also in the N.W. Again on September 17, with the wind S.E. 

 and weather fine, the air was one degree colder than the water. 



From September 20 to the end of December the new thermometer 

 was in use, and it is observable that from that date to October 7 the 

 temperature of air and water approximated very nearly, the water as a 

 rule being the colder of the two. From October 9, however, there are 

 several exceptions to this rule, notably on the 13th and 14th, when the 

 water-temperature was 4° higher than that of the air, the latter having 

 fallen suddenly some 6° in two days, and the water only 2° during the 

 same interval. The same was the case on October 25, with the wind 

 N.N.W. and the weather fine. In November and December the fluctua- 

 tions in the relative temperatures of air and water were frequent, but, 

 speaking generally, the water-temperature was higher than that of the 

 air — the greatest difference between them being on December 29, on which 

 date the air registered 26°-5, and the water 40°-3, a difi'erence of 13°"8. 

 This is the coldest day recorded, with the wind S.W. and weather fine. 



In conclusion it should be mentioned that the prevailing direction of 

 the wind in Canterbury and neighbourhood for the greater part of the 

 year is from the S. W., veering to W. and N.W. In the spring of the year 

 it is from the E., veering to E.N.E. and N.B. At such period the tem- 

 perature of the air is invariably colder than that of the water, the 

 atmosphere very dry, and plenty of dust flying about. At other seasons 

 of the year when the wind is from the S. and S.W. the reverse is the 

 case, i.e., the water is the colder of the two. The highest aii'-temperature 

 recorded in these observations was on June 7, viz., 74°, while the water- 

 temperature on the same date was 62°. 



Notes on the Temperature of Air and Water as taken at the River Stour, 

 Canterbury, during 1890. By Colonel W. H. Horslet, B.E. 



In the report for 1889 it was stated that in the months of November 

 and December the fluctuations in the relative temperatures of air and 

 water were frequent, but speaking generally, the water-temperature was 

 higher than that of the air. The same remark applies to the observa- 

 tions taken in January 1890, though there are some remarkable excep- 

 tions, showing that the temperature of water is not influenced so quickly 

 as that of the air. For instance, the temperature of the air, which had 

 averaged 39° in the first five days of January, suddenly rose on the 6th 

 to 51°'3, while that of the water, which had been 44° on the 5th, only 

 rose 1°'6 on the 6th of the same month. The same was the case on 

 January 12 — air 51°, water 48°, with wind S.W. and W. And again, 

 on the 16th and 19th, air 50°-3, water 47°"5, on the last-mentioned date. 

 Another remarkable instance is reported on January 25, viz., air-tem- 

 perature 54°, and that of water 44°-5, difi'erence 9°-5, that of air having 

 risen suddenly from 37° on the 24th to 54° on the 25th, while that of 

 the water had only risen 2°"5 in the same interval. The weather 

 throughout January was unusually mild, the wind for the most part S.W. 

 with occasional rain. 



In February the temperature of the water was, with one exception, 

 higher than that of the air. The exception occurred on the 13th, the 

 temperature of the air rising suddenly from 31° to 45°, while that of the 

 water rose only 1°, viz., from 39° to 40°. 



In March there was a remarkably sudden fall in the temperature of 

 the air, viz., from 29° on the 3rd to 14° on the 4th. The frost on that 



