2 



Pr()cee(fi)ujs of the Boyal IriHit Acadmuj, 



in ; but this falling part of the curve is made up of three crests, and 

 these three points lie in a straight line. If we now draw on the chart, 

 with a ruler, a straight line touching these three crests, and then a 

 second straight line from the commencement of the curve to the depres- 

 sion between the second and third crest, and if these two straight lines 

 are produced until they meet, the point of intersection will lie over the 

 next coming cyclone (fig. 1). 



At once the three points are found to lie in a straight line, it 

 is possible to foretell the advent of a coming cyclone. Sometimes these 

 curves follow each other in succession, and then again they may only 

 come occasionally ; but I have never found a ease where the three 

 points lie in a straight line, that the lines, if produced, will not lie on 

 the advancing cyclone. 



Fig. 1. 



The Athenreum Club in London have an instrument of the same 

 scale as mine ; and I thought it would be of interest to compare the 

 simultaneous curves taken in London and Daramona. As far as I 

 compared them, I found that there was no such type of curve produced 

 in the London record ; but some records taken at Valentia and at 

 Glasgow gave them. 



Fitzgerald suggested that it might be necessary for the production 

 of these curves that the record be taken not too far from the track 

 of the cyclone. The usual track of cyclones is along the west coast of 

 Ireland and into the North Sea. London may thus be too far for 

 these curves to be produced. 



From December, 1889, to December, 1890, there were recorded 

 nine characteristic curves. After that date the systematic search for 

 them was discontinued ; but several cases have since been recorded, 

 the gront stoim system of February 27, 1903, being a fine example. 



