OCEANOGRAPHICAL INVESTIGATIONS 3 



The expedition of Edmund Halley, Astronomer-Royal, in Haiiey's 

 1699, to improve our knowledge concerning longitude and the expedition. 

 variation of the compass, was a purely scientific voyage, though 

 it may be said that scientific voyages were really initiated at 

 the time of James Cook in the second half of the eighteenth 

 century. 



Cruquius introduced bathymetrical contours on a chart of the Bathymetricai 

 River Merwede published in 1728. Thus contour lines were Jownonmips. 

 first used on maps to show the depths of the sea and not the cruquius. 

 heights of the land. 



In a map published by Philippe Buache in 1737 we find the Buache. 

 bottom of the sea again represented by isobathic curves, 

 intended to show that certain elevations of the sea-floor 

 correspond to the orography of the neighbouring land. He 

 develops these ideas in his Essay on Physical Geography, 

 published in 1752, maintaining that the globe is sustained by 

 chains of mountains crossing the sea as well as the land, 

 forming as it were the framework of the globe — a view 

 previously expressed by Father Athanasius Kircher. His Kirchei. 

 conception of submarine mountains was a first step towards 

 founding geography on the real form and relief of each region. 



The dredge seems to have been first used by two Italians, First use of 

 Marsigli and Donati, about the year 1750, for obtaining marine ''^'^^•^^se- 

 organisms from shallow water, and a modification of this form Doiiatf/^"*^ 

 was introduced by O. F. Muller in 1799, which was known as o. f. Muiier. 

 the naturalist's dredge. 



In the middle of the eighteenth century Dalrymple and Temperature 

 Davy made observations on the temperature of the equatorial observations. 

 currents during a voyage to the East Indies. anc/Da?)!^ 



In 1770 Benjamin Franklin published the first map of the Benjamin 

 Gulf Stream (see figure in Chapter V.), and in 1776 Charles F'^nkiin. 

 Blagden was engaged in the study of temperature distribution ^^^g^'*^"- 

 on the North i^merican coasts, reporting on his results to the 

 Royal Society of London in 1781. 



During Cook's voyages (1772-73), temperature observations James Cook, 

 beneath the surface were taken by the Forsters, father and son. The Forsters. 

 but the first use of self-registering thermometers for determining 

 the temperature beneath the surface of the sea was during Lord 

 Mulgraves' expedition to the Arctic in 1773 by Dr. Irvine, who Irvine. 

 seems also to have constructed a water-bottle for bringing up 

 water-samples from various depths, one sample giving a reading 

 of 40^ Fahr., while the surface temperature was 55^ Fahr. 



