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others； invented a screw propeller。 But； while those others had
given up the idea of prosecuting it to its completion； Smith
stuck to his invention with determined tenacity； and never let it
go until he had secured for it a complete triumph。 As Mr。
Stephenson observed at the engineer's meeting： 〃Mr。 Smith had
worked from a platform which might have been raised by others； as
Watt had done； and as other great men had done； but he had made a
stride in advance which was almost tantamount to a new invention。
It was impossible to overrate the advantages which this and other
countries had derived from his untiring and devoted patience in
prosecuting the invention to a successful issue。〃 Baron Charles
Dupin compared the farmer Smith with the barber Arkwright： 〃He
had the same perseverance and the same indomitable courage。
These two moral qualities enabled him to triumph over every
obstacle。〃 This was the merit of 〃Screw〃 Smiththat he was
determined to realize what his predecessors had dreamt of
achieving； and he eventually accomplished his great purpose。
Footnotes for Chapter II。
＇1＇ In the Transactions of the Institution of Naval Architects
for 1860； it was pointed out that the general dimensions and form
of bottom of this ship were very similar to the most famous
line…of…battle ships built down to the end of last century； some
of which were then in existence。
＇2＇ According to the calculation of Mr。 Chatfield； of Her
Majesty's dockyard at Plymouth； in a paper read before the
British Association in 1841 on shipbuilding。
＇3＇ The phrase 〃wooden walls〃 is derived from the Greek。 When
the city of Athens was once in danger of being attacked and
destroyed； the oracle of Delphi was consulted。 The inhabitants
were told that there was no safety for them but in their 〃wooden
walls；〃that is their shipping。 As they had then a powerful
fleet； the oracle gave them rational advice； which had the effect
of saving the Athenian people。
＇4＇ An account of these is given by Bennet Woodcraft in his
Sketch of the Origin and Progress of Steam Navigation； London；
1848。
＇5＇ See Industrial Biography； pp。 183…197；
＇6＇ The story is told in Scribner's Monthly Illustrated Magazine；
for April 1879。 Ericsson's modest bill was only 15；000 for two
years' labour。 He was put off from year to year； and at length
the Government refused to pay the amount。 〃The American
Government；〃 says the editor of Scribner； 〃will not appropriate
the money to pay it； and that is all。 It is said to be the
nature of republics to be ungrateful； but must they also be
dishonest？〃
＇7＇ Memoirs of the Life and Services of Rear…Admiral Sir William
Symonds； Kt。； p。 332。
CHAPTER III。＇1＇
JOHN HARRISON： INVENTOR OF THE MARINE CHRONOMETER。
No man knows who invented the mariner's compass； or who first
hollowed out a canoe from a log。 The power to observe accurately
the sun； moon； and planets； so as to fix a vessel's actual
position when far out of sight of land； enabling long voyages to
be safely made； the marvellous improvements in ship…building；
which shortened passages by sailing vessels； and vastly reduced
freights even before steam gave an independent force to the
carriereach and all were done by small advances； which together
contributed to the general movement of mankind。。。。 Each owes all
to the others。 The forgotten inventors live for ever in the
usefulness of the work they have done and the progress they have
striven for。〃H。 M。 Hyndman。
One of the most extraordinary things connected with Applied
Science is the method by which the Navigator is enabled to find
the exact spot of sea on which his ship rides。 There may be
nothing but water and sky within his view； he may be in the midst
of the ocean； or gradually nearing the land； the curvature of the
globe baffles the search of his telescope； but if he have a
correct chronometer； and can make an astronomical observation； he
may readily ascertain his longitude； and know his approximate
positionhow far he is from home； as well as from his intended
destination。 He is even enabled； at some special place； to send
down his grappling…irons into the sea； and pick up an electrical
cable for examination and repair。
This is the result of a knowledge of Practical Astronomy。 〃Place
an astronomer；〃 says Mr。 Newcomb； 〃on board a ship； blindfold
him； carry him by any route to any ocean on the globe； whether
under the tropics or in one of the frigid zones； land him on the
wildest rock that can be found； remove his bandage； and give him
a chronometer regulated to Greenwich or Washington time； a
transit instrument with the proper appliances； and the necessary
books and tables； and in a single clear night he can tell his
position within a hundred yards by observations of the stars。
This； from a utilitarian point of view； is one of the most
important operations of Practical Astronomy。〃＇2＇
The Marine Chronometer was the outcome of the crying want of the
sixteenth century for an instrument that should assist the
navigator to find his longitude on the pathless ocean。 Spain was
then the principal naval power； she was the most potent monarchy
in Europe； and held half America under her sway。 Philip III。
offered 100；000 crowns for any discovery by means of which the
longitude might be determined by a better method than by the log；
which was found very defective。 Holland next became a great
naval power； and followed the example of Spain in offering 30；000
florins for a similar discovery。 But though some efforts were
made； nothing practical was done； principally through the
defective state of astronomical instruments。 England succeeded
Spain and Holland as a naval power； and when Charles II。
established the Greenwich Observatory； it was made a special
point that Flamsteed； the Astronomer…Royal； should direct his
best energies to the perfecting of a method for finding the
longitude by astronomical observations。 But though Flamsteed；
together with Halley and Newton； made some progress； they were
prevented from obtaining ultimate success by the want of
efficient chronometers and the defective nature of astronomical
instruments。
Nothing was done until the reign of Queen Anne； when a petition
was presented to the Legislature on the 25th of May； 1714； by
〃several captains of Her Majesty's ships； merchants in London；
and commanders of merchantmen； in behalf of themselves； and of
all others concerned in the navigation of Great Britain；〃 setting
forth the importance of the accurate discovery of the longitude；
and the inconvenience and danger to which ships were subjected
from the want of some suitable method of discovering it。 The
petition was referred to a committee； which took evidence on the
subject。 It appears that Sir Isaac Newton； with his
extraordinary sagacity； hit the mark in his report。 〃One is；〃 he
said； 〃by a watch to keep time exactl