Davy,--the preventing

the corrosion of the copper; but it failed as a cure of the evil,

by producing one of an OPPOSITE character; either by preserving

too perfectly from decay the surface of the copper, or by

rendering it negative, it allowed marine animals and vegetables

to accumulate on its surface, and thus impede the progress of the

vessel



Other instances might, if necessary, be adduced, to show that

long intervals frequently elapse between the discovery of new

principles in science and their practical application: nor ought

this at all to surprise us Those intellectual qualifications,

which give birth to new principles or to new methods, are of

quite a different order from those which are necessary for their

practical application



At the time of the discovery of the beautiful theorem of Huygens,

it required in its author not merely a complete knowledge of the

mathematical science of his age, but a genius to enlarge its

boundaries by new creations of his own Such talents are not

always united with a quick perception of the details, and of the

practical applications of the principles they have developed,

nor is it for the interest of mankind that minds of this high

order should lavish their powers on subjects unsuited to their

grasp



In mathematical science, more than in all others, it happens that

truths which are at one period the most abstract, and apparently

the most remote from all useful application, become in the next

age the bases of profound physical inquiries, and in the

succeeding one, perhaps, by proper simplification and reduction

to tables, furnish their ready and daily aid to the artist and

the sailor



It may also happen that at the time of the discovery of such

principles, the mechanical arts may be too imperfect to render

their application likely to be attended with success Such was

the case with the principle of the hydrostatic paradox; and it

was not, I believe, until the expiration of MrBramah's patent,

that the press which bears his name received that mechanical

perfection in its execution, which has deservedly brought it into

such general use



On the other hand, for one person who is blessed with the power

of invention, many will always be found who have the capacity of

applying principles; and much of the merit ascribed to these

applications will always depend on the care and labour bestowed

in the practical detail



If, therefore, it is important to the country that abstract

principles should be applied to practical use, it is clear that

it is also important that encouragement should be held out to the

few who are capable of adding to the number of those truths on

which such applications are founded Unless there exist peculiar

institutions for the support of such inquirers, or unless the

Government directly interfere, the contriver of a thaumatrope may

derive profit from his ingenuity, whilst he who unravels the laws

of light and vision, on which multitudes of phenomena depend,

shall descend unrewarded to the tomb



Perhaps it may be urged, that sufficient encouragement is already

afforded to abstract science in our different universities, by

the professorships established at them It is not however in the

power of such institutions to create; they may foster and aid the

development of genius; and, when rightly applied, such stations

ought to be its fair and honourable rewards In many instances

their emolument is small; and when otherwise, the lectures which

are required from the professor are not perhaps in all cases the

best mode of employing the energies of those who are capable of

inventing



I cannot resist the opportunity of supporting these opinions by

the authority of one of the greatest philosophers of a past age,

and of expressing my acknowledgments to the author of a most

interesting piece of scientific biography In the correspondence

which terminated in the return of Galileo to a professorship in

his native country, he remarks, "But, because my private lectures

and domestic pupils are a great hinderance and interruption of my

studies, I wish to live entirely exempt from the former, and in

great measure from the latter And, in

another letter to Kepler, he speaks with gratitude of Cosmo, the

Grand Duke of Tuscany, who "has now invited me to attach myself

to him with the annual salary of 1000 florins, and with the title

of Philosopher and principal Mathematician to his Highness,

without the duties of any office to perform, but with most

complete leisure; so that I can complete my treatise on

Mechanics,