492 REPOET— 1891. 



contain some apparently new observations on the protective character of 

 a sheet of ice against the cooling of water by radiation. The rapid fall 

 of temperature following a thaw is analogous to the effect observed on 

 earth thermometers not far from the surface in like conditions. 



Notes on the Txiver Temperatures for the Winter 1890-91 in the Nicld. 

 By Mr. G. Paul, Knareslorough. 



Some very interesting effects were observed dui'ing the long period 

 of intense cold. The river was frozen over, but the water under the ice 

 remained at the constant temperature of 84<°'0 from December 20 to 

 January 2 inclusive. It fell to 33° on thawing on Januai'y 3. On 

 January 6 a second period of ice on the water commenced, and daring it 

 the temperature under the ice remained at 33°'0. Not until the next 

 thaw set in and a tliird frozen period commenced on February 27, did the 

 temperature of the water under the ice fall to 32°'0. 



Compared with this the record of earth-temperature at tlie depth of 



1 foot acquires a special interest. An ice-cap was formed on the ground 

 on December 21 and remained until January 21. During this entire 

 month the temperature at the depth of 1 foot scai-cely varied. On 

 December 20, before the severe cold set in, the temperature at that depth 

 was 37°-4, on the 21st it fell to 36°-5, next day to 36°-4, and until 

 January 4 its range was only between 3G°'4 and 36°'3. From January 



2 to 17 the temperature at 1 foot was 36°-3 or 36°-2 ; on the 18th it fell 

 to36°'0, and on that day the grass thermometer registered only 3°"8, the 

 minimum temperature of the winter. On January 20 the 1-foot earth 

 thermometer registered 36°'4, but on the 21st it fell to 35°'5, coincident 

 with a rise of air-temperature and a general thaw. Next day the tem- 

 perature at 1 foot had risen to o6°'2, and did not again fall below this 

 value. 



The rest of the observations are given in the form of tabulated 

 monthly means and of curves expressing the weekly means. Had time 

 and other circumstances permitted, many or all of these sets of observations 

 would have been fully discussed, but the mere record suggests many 

 interesting relations as to the period of maximum and minimum tem- 

 perature, the manner in which watei'- temperature follows air-temperature, 

 and the effect of situation in latitude and altitude on the rate and amount 

 of monthly change. . 



Bristol Channel and TAFf. 



The Cardiff Naturalists' Society arranged for three sets of observa- 

 tions from February 1889 to July 1891. One was taken by Mr. Petti- 

 grew in the Cardiff Castle Gardens on the Dock Feeder, a large stream 

 diverted from the Taff. This set of observations (Curve XII.) shows 

 the water-temperature to be always higher than that of the air. This 

 is the only case in which this relation, so cleai'ly shown in the Cherwell 

 observations, was distinctly seen in another river. 



The Breaksea Lightship is anchored in the Bristol Channel about the 

 centre, south of Barry Island. Observations were made on it daily at 

 9 A.M. by Mr. J. Walters and Mr. J. R. Johnson. The record (Curve X.) 

 shows that while the temperature is rising, from February to July, the 

 water is colder than the air ; but when the temperature is falling, from 



