288 Britain's Heritage of Science 



In addition to these fundamental conceptions which have 

 done so much to clear up the structure of widely differ- 

 ing animals, Lankester has introduced many new terms 

 which have proved of permanent value in the science of 

 zoology. Amongst these may be mentioned " nephridium," 

 " blastoderm," " stomodeum," " proctodeum." Further, 

 he introduced the terms "" homogeny " and " homoplasy," 

 to distinguish between the two very different senses in which 

 " homology " had previously been used. 



As a maritime nation, Great Britain has led the way in 

 exploring the plant life and animals of the sea, the chemical 

 and physical nature of the sea water, and the geological 

 structure of the subaqueous earth. As long ago as 1749 

 Captain Ellis found that a thermometer, lowered on separate 

 occasions to depths of 650 fathoms and 891 fathoms respec- 

 tively recorded, on reaching the surface, the same tempera- 

 ture, namely, 53. His thermometer was lowered in a 

 bucket ingeniously devised so as to open as it descended 

 and close as it was drawn up. The mechanism of this instru- 

 ment was invented by the Rev. Stephen Hales, D.D., to 

 whom we have referred above. Dr. Hales was an ingenious 

 soul and the author of many inventions, amongst others, 

 he is said to have suggested the use of the inverted cup 

 placed in the centre of a fruit-pie in which the juice 

 accumulates as the pie cools. His device of the closed 

 bucket with two connected valves was the forerunner of 

 the numerous contrivances which have since been used for 

 bringing up sea-water from great depths. The colour of 

 the sea and its salinity had also received attention in early 

 days, notably at the hands of the distinguished chemist, 

 Robert Boyle. 



The invention of the self -registering thermometer by 

 Cavendish in 1757, provided another instrument essential 

 to the investigation of the condition of things at great 

 depths, and it was used in Lord Mulgrave's expedition to 

 the Arctic Sea in 1773. On this voyage attempts at deep- 

 sea soundings were made, and a depth of 683 fathoms was 

 registered. During Sir James Ross's Antarctic Expedition 

 (1839-1843) the temperature of the water was constantly 

 observed to depths of 2,000 fathoms. His uncle, Sir John 



