KEY AND INDEX 



"doctrine of irritability," for which he has been 

 called "the father of modern nervous physiol- 

 ogy-" 



Halley, Edmund, iii, 7. Born at Haggerston, 

 England, Oct. 29, 1659; died at Greenwich, 

 Kent, 1742. English astronomer and mathema- 

 tician. Before he was nineteen he had published 

 a work which supplied a defect in Kepler's the- 

 ory of planetary motion. At the age of twenty 

 he established the certainty of the motion of the 

 sun round its own axis by his observation of a 

 sun spot. In 1720 he was appointed Astronomer 

 Royal at Greenwich. His popular fame rests on 

 his observation of the comet named for him, and 

 whose orbit is of such size that the comet makes 

 its appearance only once in every 76 or 77 years. 

 In all this comet has appeared 26 times during 

 the historic period of which we have any record. 

 Its first appearance was in the year n B.C., its 

 last in 1910. 



Hargreaves, James, ix, 16. Born at Black- 

 burn, Lancashire, England; died at Nottingham, 

 April, 1778. English mechanic and inventor. 

 His invention of the spinning-jenny, patented in 

 1770, revolutionized the spinning industry. 



Harrison, John, vii, 25. Born at Yorkshire, 

 England, March 31, 1698; died at London, 

 March 24, 1776. English mechanician and in- 

 ventor. He invented the compensating pendu- 

 lum, by the use of which clocks could be made 

 accurate time-keepers regardless of surrounding 

 temperature. He also invented the chronome- 

 ter, and was finally awarded the prize of twenty 

 thousand pounds offered by the British Govern- 

 ment for such a timepiece. 



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