BY G. R. SM ALLEY, ESQ. 355 



and it is only by a long series of careful and systematic observa- 

 tions well reduced and collected, that such laws can be arrived at. 

 I could wish, indeed, that every health-officer and medical 

 practitioner, whether in his public or private capacity, might be 

 persuaded to devote some attention to the presence of that agent 

 which we call ozone for want of a better term ; and also to the 

 presence of humidity at any time, as indicated by the readings 

 of the wet and dry bulb thermometers. Nor are magnetical 

 observations of less practical importance. Their relations to 

 meteorology have been already alluded to. They are of the 

 utmost importance to the surveyor in the interior of a country : 

 and still more so to the mariner along a rocky iron-bound coast. 



It is to be hoped that the whole of this colony will be 

 surveyed on a sound scientific basis, but according to the 

 method hitherto adopted, some idea may be formed of the impor- 

 tance of magnetic operations, when I state that the boundary 

 line of an estate, might, in the course of 60 years, be found to 

 differ from the original determination by upwards of a degree, 

 owing to the secular variation of the magnetic meridian. 



The whole range of magnetic observations is called into 

 active play in the determination of the error produced in the 

 ship's compass by the attraction of the iron, in the several parts ; 

 for want of such determination there is reason to suppose that 

 many a good and well found ship, has been cast away. 



The advantages of a magnetic survey of this country I propose 

 to discuss more fully upon a future occasion, at the present time 

 I will confine myself to an illustration of some practical import- 

 ance. In commencing this survey I determined to take such 

 stations as were most convenient, at intervals of about 15 miles, 

 and without any enquiries as to possible local imfluence. I 

 decided thus, because I believe that most localities in this country 

 have more or less local influence, and whilst it would be easy 

 afterwards to reject from the magnetic chart suspected stations, 

 yet it would be far from easy to determine from enquiries made 

 before-hand, what localities were certainly free from causes which 

 would influence the observations. Three of my stations, Nobby's 

 at Newcastle, Musclebrook, and Wingen, (near what is called 

 the Burning Mountain) exhibited singularly discordant results. 



