^0 ALLISON — ON METEOROLOGY. 



11 times the temperature fell to or below. 



11 gales were noted. 



A remarkable Lunar Halo on evening of 12th February, as 

 observed in the record of that month. 



But twice did thunder storms occur. 



On 42 days there wrts fog. 



On 183 days v*-e had frost. The longest period that it was 

 absent was from 11th June to 12th Septeniber ; tho earliest four 

 viz : 12th, 15th and 24th September, and 1st October, read from 

 ground thermometer. This harbour was open throughout the 

 whole year. I notice that in the proceedings of the Institute, 

 your late esteemed and worthy member Col. Myers, reviewing 

 meteorologically the year 18fi6, says, while noting as remarkable 

 the fact that the harbour froze over with a temperature of 7 be- 

 low on 7th Fc!>ruary, 1)ut did not do so on 7th January at 15 

 below 0, that " it must be borne in mind that a combination of 

 wo coiiditions of the weather is required, viz. : a perfect calm 

 with a certain hr.v state of the temperature, without which the 

 harbour does not freeze ; ;ind to this may perhaps be attributed 

 the iiifrequencj of what was witnessed last winter." Now, no 

 doubt this is true, and partially accounts ior the event; but we 

 nuist also remem[)er, that up to a certain point, before the sun 

 has again attained aiiy great height, the water itself is giving off 

 its own heat, and later in the winter there is not the same resis- 

 tance in it to be overcome, that there is at an earlier date when 

 the effects of the heat of the past summer are comparatively 

 recent; and therefore from this cause alone, ccEteris paribus, a 

 -a large bodv of water in motion would freeze at a hio-her 

 •temperature of the atmosphere in February than iii December ; 

 i. e., it would then be more readily assimilated to that atmos- 

 phere in its own temperature. The same holds good with the 

 land ; and is indeed the chief reason why we do not, as a n^iatter 

 of course, experience our greatest heat when the sun's rays are 

 most nearly vertical, in June; and the contrary in December; 

 M'hereas wc all know that our maximum of heat is most likel}'' 

 t(; occur lull a month after the longest dav, and our minimum as 

 much after the day when the sun is lowest; so that the sun's 

 j-ays and the earth's surface acting together upon the atmosphere, 



