148 On the Method of Calculating the Increment 



One reason for adopting the new zero was that negative 

 numbers and measurements in dealing with tide-gauge 

 records, or soundings in surveys, would be thus avoided. 



It is to be regretted that no precise references of mean 

 tide level in the earlier days can be found. Where 

 measurements do exist they are lacking in accurate 

 information as to state of tides, and I can find nothing 

 trustworthy upon which to base any statement as to 

 change of sea-level since surveys have been made. I 

 think it desirable that permanent bench marks on the 

 natural beds or faces of rocks in situ should be established 

 around our bay, carefully connected by accurate levelling 

 with one another and with the tide-gauge, for it is very 

 doubtful if bench marks on buildings can be assumed to 

 afford a permanent datum. 



Art. VIII. — On the Method of Calculating the Increment 

 in itte Value of Land. 



By Alexander Sutherland, M.A. 



[Read 14th August, 1879.] 



It ought to be well enough known in these enlightened 

 times that a sum of money invested for a long term of years 

 at a fair rate of interest, without being disturbed, will be con- 

 verted into a sum quite enormous compared with the 

 original investment ; and yet the public mind is from time 

 to time disturbed by fallacies originating in a comparison of 

 first sum and its result without allowing for the action of 

 compound interest. A man, for instance, may have spent 

 £100 in buying a piece of land fifty years ago ; he may have 

 done nothing with it, and yet the land may now be worth 

 the handsome little fortune of £11,731. When people learn 

 this fact they are surprised beyond measure, and imagine 

 the case quite exceptional ; they fancy the man has got an 

 enormous profit, and some of his poorer neighbours look 

 upon the process as almost dishonest ; whereas, as a matter 

 of fact, he has got only 10 per cent, per annum on his invest- 

 ment. The present form that this fallac} 7 takes is the 

 demand that Government should retain possession of the 



