Early 



soundines. 



Cusanus" 

 bathometer. 



Puehler's 

 apparatus. 



Alberti's 

 apparatus. 



Hooka's 



apparatus. 



First sound- 

 ings laid down 

 on maps. 



First attempt 

 at deep-sea 

 sounding. 



Magellan. 



2 DEPTHS OF THE OCEAN chap. 



From time immemorial soundings were taken by hand 

 with a plummet, always in shallow water near land, but attempts 

 have not been wanting to sound the ocean without the aid of a 

 line. Thus about the middle of the fifteenth century Cardinal 

 Nicolaus Cusanus invented a bathometer, consisting of a hollow 

 sphere with a heavy weight attached by means of a hook ; on 

 touching the bottom the weight was detached, and the sphere 

 returned to the surface, the interval of time from the launching 

 of the apparatus to the re-appearance of the sphere at the 

 surface indicating the depth. A century later Puehler improved 

 on Cusanus' bathometer by adding a piece of apparatus 

 (clepsydra) to measure the time from the disappearance to the 

 re-appearance of the float, using for this purpose a clay vase 

 with a small orifice at the bottom, through which water was 

 made to enter during the period of the experiment, the amount of 

 water in the vase indicating the depth. Alberti subsequently 

 replaced the sphere by a light, bent metal tube. In 1667 

 Robert Hooke described in the Philosophical Transactions a 

 similar apparatus, shown in the tailpiece to Chapter IV., with 

 which experiments were made in the Indian Ocean, but there 

 was always doubt as to the moment when the float returned 

 to the surface, and to remedy this Hooke introduced first a 

 clockwork odometer to register the descent, and then two 

 odometers — one for the descent and the other for the ascent. 

 These various forms of bathometers, though interesting historic- 

 ally, proved of little practical value. 



Soundings in shallow water first appeared on a map by 

 Juan de la Cosa in 1504, and soundings were laid down 

 on maps by Gerard Mercator in 1585 and by Lucas Janszon 

 Waghenaer in 1586. 



Probably the first attempt at oceanographical research to 

 which the term " scientific " may be applied is Magellan's 

 unsuccessful effort to determine the depth of the Pacific Ocean 

 during the first circumnavigation of the globe. In 1521, we 

 are told, Magellan tried to sound the ocean between the two 

 coral islands, St. Paul and Los Tiburones in the Low Archi- 

 pelago, making use of the sounding lines carried by explorers 

 at that period, which were only 100 to 200 fathoms in length. 

 He failed to touch bottom, and therefore concluded that he had 

 reached the deepest part of the ocean. This first authentic 

 attempt at deep-sea sounding ever made in the open sea is 

 historically extremely interesting, though scientifically the result 

 was negative. 



