514 Transactions. 



As to the depth of wells, it appears that in the various oil- 

 bearing districts there is a great difEerence in the depths, and 

 even in the same district a greater depth has to be tried after 

 wells have been running for some time, as it is found the pres- 

 sure is constantly diminisliing. The Pennsylvania wells have an 

 ■average depth from 1,600 ft. to 1,800 ft., ^feut some wells reach 

 about 3,000 ft. ; and in West Virginia they are numerous be- 

 tween 2,000 ft. and 3,000 ft., whilst one actually reaches 5,000 ft. 

 In the Baku district, bordering on the Caspian Sea, the pump- 

 ing -wells exceed 1,000 ft. in depth, and there are fountains 

 •of flowing ones much deeper than this ; and the tendency year 

 by year as new wells are put down is to sink deeper. 



These varying depths are given here to show that the depth 

 of the Moturoa well is not excessive. Wells situated within 

 continental areas may be supposed to contain larger oil-bearing 

 basins than in the case of islands like New Zealand, and over- 

 lying beds may become saturated with oil by the chemical 

 changes that may be assumed to have been in progress for long 

 periods of time. In the case of the Baku field, for instance, it 

 occupies an area where the rocks at a little distance below the 

 •surface were so saturated with oil that large quantities were 

 . obtained from wells less than 100 ft. in depth ; but these supplies 

 have ceased, and deeper wells have been put down, as in America 

 a:id elsewhere. < • i 



Regarding the depth that ought to be tried along the east 

 coast, it seems that the question is one of location. Hitherto 

 the sinkings have been inland and at a comparatively high 

 elevation, but the experience of American and other oil-explorers 

 shows that it is not essential at all to put down a bore in the 

 vicinity of a petroleum-spring. The oil usually finds a means 

 to escape along the lines of rocks that are much fractured and 

 broken, whilst the actual source of the oil may be miles away. 

 In putting down a well all indications favourable to the work 

 should be taken into account, such as gas-springs, salt springs, 

 accessibility and probable cost of carriage of material. Thus 

 it has been suggested again and again that trial bores might be 

 put down within a few miles of Gisborne at very little expense, 

 and with quite as good prospects of testing for oil as at Mangatu. 

 The rocks are certainly similar, and gas, salt, and sulphurous 

 springs are met with near Tua Motu, where the rocks indicate 

 the close proximity of the black shales by the appearance of the 

 overlying greensands. The troughing of the beds gives an 

 advantage in favour of the last-named place as compared with 

 Mangatu, and should oil ever be struck along the line indicated 

 the flow should be better towards the coast than at any place 

 further inland. 



