14 



Art. II. — Some interesting facts founded on Barometrical 

 Observations. By A. C. Gregory, Esq., E.R.G.S., &c. 



(With a Plate.) 

 [Keacl before the Institute, 30th March, 1859.] 



Sydney, 15th Dec, 1858. 

 Dear Sir, 



In the course of the investigations of the variations of the 

 barometer which were necessary for the computation of the 

 altitudes of the various portions of the interior traversed 

 by the late expedition from Moreton Bay to South Australia, 

 there appeared such a remarkable coincidence in the rise and 

 fall of mercury at stations 500 to 1000 miles distant, that I 

 constructed a diagram, exhibiting the comparative changes 

 at Adelaide, Melbourne, Sydney, and Moreton Bay. Know- 

 ing the interest you take in all branches of science, I send 

 you a copy of this diagram, as, if placed in the hands of some 

 of your scientific friends who are engaged in meteorological in- 

 vestigations, it may suggest some more perfect and effective 

 system of tracing the course of storms, &c. The reason for 

 thinking that these investigations may be of practical import- 

 ance is, that all great changes of atmospheric pressure appear 

 to take place at the South- Western stations many hours earHer 

 than at the North-Eastern ones — thus Adelaide precedes 

 Sydney by 12 to 24 hours, and it is not impossible that, 

 with the rapidly extending system of electric telegraphs, timely 

 notice of approaching storms may be transmitted from one 

 seaport to another. 



I remain, dear Sir, 



Yours very truly, 



A. C. GREGORY. 



To Dr. Ferdinand Mueller, 

 President of the Philosophical Institute of Victoria. 



