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(Colombo), Java (Batavia), Mauritius, and finally to 

 Australia (Perth, Adelaide and Sydney). 



The striking similarity between these curves shows 

 that over the whole of this area, which includes both 

 north and south latitudes, the same kind of variations is 

 in action, and that therefore the whole region is inti- 

 mately connected meteorologically. 



Attention was next paid to extending the region around 

 Cordoba, which station, as has been previously pointed 

 out, exhibits pressure variations similar to, but the inverse 

 of, those of India. 



As Cordoba represents an area south of the equator, 

 and the neighbouring stations exhibit similar pressure 

 variations, a portion of the United States of America 

 was taken as typifying an area with north latitude and 

 in about the same longitude, and a commencement was 

 made along the lowest available parallel of latitude. 



This was rendered possible by the kind- 

 ness of Prof. Bigelow, who forwarded 11 

 proof sheets of a new reduction of United 

 States pressures which he had just com- 

 pleted. 



Treating these pressures in the same 

 way as those for the Indian region, several 

 stations which had the best record were 

 chosen. A graphical representation of the 

 variations of four of these stations (Mobile, 

 Alabama ; Jacksonville and Pensacola, 

 Florida ; San Diego, California) is given 

 in Fig. 3, and for the sake of comparison 

 the pressure of Cordoba, with the inverted 

 curves representing the Bombay pressure 

 and solar prominence variation. This 

 series of curves refers in all cases to the 

 variations of the means of the high-pres- 

 sure (winter) months (October to March 

 in most cases). At Cordoba, which has 

 a southern latitude, the high-pressure 

 months extend from April to September. 



The result of the comparison shows that 

 in this region of the world we have also a 

 large area the pressure variations over 

 which are very similar to one another. 



Although the general agreement be- 

 tween the two main sets of curves is most 

 striking, there are minor differences which 

 probably will eventually help to deter- 

 mine those cases in which the prominence 

 effects on pressure are masked by some 

 special conditions. 



From these collected series of facts it 

 will be seen that, as regards similar short- 

 period pressure variations, the two regions 

 about India and Cordoba have been con- 

 siderably extended, and extended on both 

 sides of the equator in each case. 



With these two large areas indicating similar barometric 

 variations from year to year, but one showing an excess 

 while the other displayed a deficiency, new questions were 

 at once raised. It required, however, a far more general 

 barometric survey over other areas before such questions 

 could be answered, but so suggestive were the facts 

 observed that, as was stated in the paper, such an inquiry 

 was at once undertaken and is still in progress. 



It may, however, here be mentioned that already many 

 other localities have been examined. The Indian area 

 has been extended, for instance, to Aden and Egypt, the 

 former of which places is practically a counterpart of 

 India as regards these barometric variations, while the 

 latter approximates to it. If, on the one hand, we 

 denote land areas the barometric variations of which are 

 very like those of India with a positive sign, and those 

 with a positive query sign ( + ?) which are more like 

 India than Cordoba ; and, on the other, pressures 



similar to those of Cordoba with a negative sign, and 

 those which are more like Cordoba than India with a 

 negative query sign ( - ?), then it is found that, so far as 

 barometric observations which have as yet been examined 

 are concerned, the earth's surface may be divided 

 approximately into two main regions, one positive the 

 other negative, separated from one another by areas the 

 pressure variations of which may, according to the above 

 notation, be described as positive and negative queries 

 ( + ?, -?)• 



It is fortunate that while this reduction and collation of 

 barometric facts has been pursued in this country, 

 another investigator has been working on similar lines in 

 the United States, making it possible to compare results. 

 In fact, Prof. Bigelow's research, 1 which was received 

 some time after the above-mentioned was communicated 

 to the Royal Society, has led him to very nearly 



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the same conclusions as those stated in the present 

 article, if some minor differences be excluded. One of 

 these differences arises from the fact that he has formed 

 the mean of barometric observations made over an area 

 including north-east China, Japan, north India, central 

 India, south India, Batavia and Mauritius, while there 

 seems evidence to show that the whole of India, Batavia 

 and Mauritius behave differently from Siberia, northern 

 China and Japan. This, however, he somewhat concedes 

 later in his article as he points out that "in Siberia and 

 Russia the synchronism begins to break a little . . ." 

 Another difference will be referred to a little further on. 



Apart, however, from these, Prof. Bigelow finds that 

 " the same pressure variations, in fact, prevail over very 



l Monthly Weather Review, vol. xxx. No. 7, p. 347, "Studies on the 

 Statics and Kinematics of the Atmosphere in the United States, No. vii., 

 A Contribution to Cosmical Meteorology " by Prof. Frank H. Bigelow 

 (dated August 12, 1902). 



