Kihther’s Views 
AS TO THE DKITII 
or THE OciAH. 
nS THE VOYAGE OF H.M.S. CHALLENGER. 
it was almost impossible to determine exactly the moment when the float returned to 
the surface, and Hooke endeavoured to obviate this defect by a new apparatus, which 
he presented to the Royal Society in 1671. This improved “Explorator profunditatis, 
distantiae, abyssi,” had a sphere with a hole through the diameter, in the orifice of which 
lie placed an axis with inclined blades. During the descent of the bathometer a hand 
connect* 1 with clockwork was set going by an endless screw, and acted as a marker. 
As soon as the weight was detached at the bottom, a spring closed the orifice with a 
v dve and stopped the clockwork during the ascent. Lastly, a third improvement was 
introduced by Hooke. A vertical rod bore the wooden sphere intended to return to the 
surface, having on the upper part a float or buoy to show more distinctly the moment 
of emersion. The apparatus was provided, moreover, with two odometers — the one to 
register the descent, the other the ascent. The weight of the bathometer was held by 
a spring-hook ; Bacciali replaced this by clutches, the arms of which held the sphere 
during the descent and opened to let it go on touching the ground. 
These methods and bathymetrical apparatus increased but little the bathymetrical 
knowledge of the sea, and rendered insignificant services as regards soundings. The 
soundings taken during the period under consideration were made in the usual manner 
with lead and line, and were confined to spots near the coasts and in comparatively 
shallow waters. We have noted the fruitless efforts of Magellan to sound the Pacific ; 
j -art from this detail, which has only historical interest, there is little progress to record. 
Father Athanasius Kircher, in his encyclopaedic work Mundus Subterraneus, devotes 
a chapter to oceanographical questions. 1 After having given the nomenclature of the 
oceans, and indicated the subterranean rivers supposed to feed the Caspian, so often 
ii. ■ ntioned by the ancients, he examines the opinions accepted in his time as to the depths 
of the sea. His doctrine that the deepest seas were to be found opposite the loftiest 
mountains was adopted by many. Kircher sums up his opinion on the subject thus: 2 
“ In tin same manner as the highest mountains are grouped in the centre of the land, 
-.0 also should the greatest depths be found in the middle of the largest oceans ; 
near t! ■ coasts with slight elevations, the depth will gradually diminish towards 
the -hore. I say coasts with slight elevations, for if the shores are surrounded 
by high rocks, then greater depths are there found ; this is proved by experience on 
t lie shores of Norway, Iceland, and the lies de Flandres.” He imagines the bottom 
of the ocean, over its whole extent, to be very uneven. The marine plains must be 
found in those places not thronged with islands, where the declivities of the oceanic 
mountains arc not pronounced. He brings forward scanty proofs in support of 
his theory, his experiments being mostly made on the sea-shore. He concludes by 
-tying: “Ex his adducti- patet, quam hallucinentur, qui putant, maris profunditatem 
ubique at equalem ctse, aut detenninari posse certain ejus profunditatem ; tarn enim 
' Kircbfr, Mundua Subterraneua, Ainat., 1664, j*. 80. J 1 lid., p. 97. 
