50 



REPORT — 1871. 



Portuguese lias undertaken to provide tlie instruments and instruct the observer. 

 The only expense involved is the charge for the transmission of the telegraph- 

 messages : it would be most unfair that a counti-y like Portugal should bear all the 

 cost (about £3oO per annum for one message daily) ; and Dr. Ballot thinks that it 

 should be raised jointly and proportionally by the European Maritime States, all of 

 whom would largely benefit Tby the adoption of the proposal. 



Mean Temperature of ArhroatJi. Latitude 56° 33' 35" North, Longitude 

 2° 35' 30" W. of Greenwich. By Alexander Bhown, LL.D. 



The author constructed from his meteorological journals the foregoing Table for 

 the purpose of showing the Mean Annual Temperature at Arbroath, in the coimty 

 of Forfar, on the east coast of Scotland. In the Table, columns nos. 1, 2, 3, and 

 4 give the monthly mean temperature, and also the annual mean temperature, of 

 each of the years 1867, 1868, 1869, and 1870. The warmest of these four years was 

 1868, and the coldest the year inuuediately preceding, namely 1867. The mean 

 temperature of 1868, as shown by the Table, was 48^-9, and that of 1867 46°-7, the 

 difference between the warmest and coldest year of the foiu- being 2°-2. Column 5 

 is the mean of the nionthlj- and annual temperature of the four years already men- 

 tioned ; column 6 is the mean of 13 years, from 18.57 to 1869 inclusive ; co- 

 lumn 7 is the mean of 22 years, from 184-5 to 1866 inclusive ; and column 8 is the 

 mean of 26 years, from 184.5 to 1870 inclusive. The annual mean temperature of 

 the 4-year period is 47°-6, of the 13-year period 47°-0, of the 22-year period 46°-3, 

 and of the 2G-year period 46°-4. It will be observed that the annual means of the 

 two long- periods differ by only one tenth of a degree, and are therefore a near ap- 

 proximation to the mean temperature of the locality. 



The thermometers used are the Minimum thermometer of Ruthei-ford and the 

 Maximum thermometer of Negretti and Zambra, which have been tested by the 

 Standard instruments of the Scottish Meteorological Society. They are attached 

 to a wooden frame fixed to a window-sill having a northern exposure. Very gi-eat 

 care is taken to protect the instniments from the effects of radiation and other 

 causes. The thermometers are placed 11 feet from the ground and 70 feet above 

 the level of the sea, and distant therefrom 783 yards in a direct line. 



