320 F. Guthrie, LL,B. — Sea Level in South [Feb. 27, 



rather goes to shew that while we have enough good material 



from which to draw useful deductions, we have on the other hand a 



superabundance of bad material from which it is impossible to deduce 



any satisfactory conclusions whatever. No one who has not made 



himself acquainted with the facts can realize the difficulty there is in 



getting a series of trustworthy observations taken under the 



same conditions at one place, extending over even four or five years. 



What is still more unsatisfactory is that some of the fundamental 



data of meteorology are still undetermined. In drawing up this 



table, for example, it was necessary to ascertain as exactly as possible 



the average sea level barometric pressure round the South African 



Qoast. This is very imperfectly known. The estimates of sea 



level pressures at different latitudes, in the best works on 



meteorology, are very rough and imperfect, and as far as 



South Africa is concerned it may safely be said that it is 



only here in the neighbourhood of the Royal Observatory where 



careful observations have been made for almost fifty years that we 



have anything approaching accurate knowledge on this subject. 



Mr. Stone the former Astronomer-Royal of the Cape Observatory 



calculated this out from the long series of observations taken at the 



in. 

 Observatory and deduced a sea level barometric pressure of 30*067 



in. 

 with a daily average variation of from "0214: below that at 4 p.m. 



in. 

 to '0243 above at 10 a.m. There seems some reason to suppose that the 



average sea level pressure increases very slightly towards Port 



Elizabeth, and there can be no doubt that there is a very perceptible 



increase when the coast trends towards the North, as at East 



London and Durban. The average pressure at Durban is probably; 



about a maximum. Beyond that latitude the known equatorial depres-"- 



sion should begin to be felt. What we know nothing about is how 



far the daily variations which Mr. Stone ascertained to exist here 



at Cape Town can be applied toother parts of the Colony and especially 



to inland stations. It may be regarded as some slight argument 



that the daily variations are substantially the same elsewhere as 



they are here, that in compiling this table observations taken at 



different times of the day at different localities have been reduced 



to 8 a.m. according to Stone's table of reduction, and the result as 



far as it can be tested is fairly satisfactory. 



The delay which has occurred in the publication of this paper in 



the Transactions of the Society has enabled the writer to make 



