424 



MR. G. V. VERNON ON 



were really true^ as then all the variations would vanish. 

 The very irregular nature of these variations shows how 

 little dependence can be placed upon results deduced from 

 the observations of a few years^ and how useless it is to 

 attempt making empirical laws in the present state of our 

 knowledge. 



The period from 1781 to 1791 appears to have been that 

 in which the variations below the average were at their 

 maximum, eveiy year but 1781 being below the average. 

 From 1841 to 1851 there was only i year below the average, 

 and from 185 1 to 1861 only 2 years below the average. 



A careful examination of the entire period, as shown in 

 the diagram, very clearly points out that these variations 

 obey no law of periodicity. That the variations do not 

 balance one another during the same year is very evident. 



Table I. 



Year. 



Sum of 

 + dif- 

 ferences. 



Sum of 

 - dif- 

 ferences. 



Excess of 

 -f read- 

 ings. 



Excess of 

 — read- 

 ings. 



Number of 



months 

 above the 

 average tem- 

 perature. 



Number of 



months 

 below the 

 average tem- 

 perature. 



1771. 

 1772. 

 1773- 

 1774- 

 1775- 

 1776. 



1777. 

 1778. 

 1779. 

 1780. 

 1781. 

 1782. 



1783- 

 1784. 

 1785. 

 1786. 

 1787. 

 1788. 

 1789. 

 1790. 

 1791. 







4*5 



6-2 



r6 



rs 



23"9 

 12-3 



io'7 



217 



35-7 



237 



18-9 



3'2 



9'5 



37 

 1-8 



57 

 IO-3 



5"i 

 8-6 



io'4 



39'6 



20-8 



22-5 



129 



3-3 



I2'5 



117 

 10-5 



I '4 

 17-2 



15 



367 

 1 3^3 

 44-0 

 26-1 

 321 

 8-2 

 15-8 



24*3 

 II-6 



132 





 206 



1 1-2 



34-3 



6-5 



17-4 



• 







35-i 

 I4-6 



20"9 



5 "4 



0-2 

 I'O 



33'5 



3-8 



38-8 



22'4 

 30-3. 



5-5 



19'2 



3-0 



2-8 



2 



4 



2 



5 

 10 



9 



5 

 7 

 9 

 7 

 10 

 I 



7 

 2 



5 

 2 

 6 



5 

 3 

 5 

 6 



10 



8 



9* 



7 

 2 



3 



7 



5 

 2* 



5 



2 



II 



5 

 10 



7 

 '? 



7 



9 

 6* 



6 



* One month exactly the average. 



