and intensity of the Magnetic Needle. 



857 



The above is a general mean view of these curious observations, 

 and the following Table contains the mean results of the experi- 

 ments on intensity. A needle, as we have stated, was kept specifi- 

 cally for the intensity experiments. These were made and regis- 

 tered every hour, by noting the time the needle required to make 

 60 vibrations ; and the following Table is a general mean for the 

 same hour for all the days in each month. It should be observed, 

 however, that, on the 1st of May, for some reason not stated, the 

 needle was magnetized. The general mean is therefore exclusive 

 of May. 



Monthly and Genei'al Mean Intensities of the Horizontal Magnetic 

 Needle for every Hour for Four Months. * 



We come now to a highly important part of these experiments, 

 and which we owe to a very happy thought of Lieutenant Foster's, 

 while pursuing the two series we have endeavoured to describe ; 

 and which cannot be better illustrated than by using the author's 

 own words. The article here referred to is the seventh in the vo- 

 lume, and is entitled '^ A Comparison of the Diurnal Changes of In- 

 tensity in the Dipping and Horizontal Needles at Port Bowen." 

 These are introduced by the author in the following terms : 



* In the above Table a few errors have been detected in obtaining the 

 means, and are corrected. 



JAXUAEY MARCH 1827- A a 



