White. — Was there a Sivimming Moa? 339 



has the advantage that the induced current received is in- 

 stantaneous instead of being a gradually increasing amount, 

 as when no condenser is used. 



There are other advantages arising from the use of con- 

 densers. They prevent earth currents from entering the 

 cable. One part of the earth's surface may differ very con- 

 siderably from another part in regard to the amount or poten- 

 tial of the electricity there. If these places are connected by 

 a wire an electric current will traverse it. These currents 

 sometimes interfere with the working of the telegraph where 

 the line is not fitted with condensers. A faulty cable may be 

 used for a long period by being insulated with condensers. If 

 the fault is considerable enough to allow sea-water to pene- 

 trate to the copper, we have all the essentials of a galvanic 

 cell — two metals (copper and the iron sheathing) in a saline ' 

 solution. The effect is to corrode the copper, and thereby 

 make the cable useless. When condensers are used the faulty 

 cable may be permanently connected to the zinc pole of a 

 battery at the shore station, whereby a negative current 

 passes out at the fault. The water there is decomposed, 

 hydrogen gas being evolved, and the cable is preserved from 

 injury. 



Ruptures of the cables across Cook Strait and the fitting 

 of a cable-repairing ship by our Government remind us of the 

 expense the proprietors of telegraph cables may be put to in 

 keeping their lines in proper repair. On the whole, while 

 our subject is of the keenest interest to the student and the 

 scientist, the results of the various enterprises are often un- 

 satisfactory to those who have invested their money. It has 

 been proposed to lay a cable across the Pacific to unite these 

 Australasian Colonies with British North America. I venture 

 to think this most desirable in the interests of the British 

 Empire as a whole. 



Art. XXXIX. — Have we the Remains of a Sivimming Swan- 

 like Moa ? 



By Taylor White. 



[Read before the Hawke's Bay Philosophical Institute.] 



In Nature, published on the 8th April, 1897, -at page 534, is 

 a letter by Professor 0. C. Marsh, of Yale University, New 

 Haven, Connecticut, dated the 16th March. This communi- 

 cation is of great interest, especially to those who, like my- 

 self, take pleasure in searching the past history of those 



