Thomas Young Quotes

[T]he lectures... may be expected to remain tolerably commensurate to the state of the sciences for a much longer period; since, in investigations so intimately connected with mathematical principles, the essential improvements will always bear a very small proportion to the number of innovations. ...the references, which it contains, are... sufficient to lead those, who may consult the passages quoted, to the works of every author of eminence that has treated of the respective subjects.

The theory of waves has been much simplified, and somewhat extended, and their motions have been illustrated by experiments... A similar method of reasoning has been applied to the circulation of the blood, to the propagation of sound, either in fluids or in solids, and to the vibrations of musical chords; the general principle of a velocity, corresponding to half the height of a certain modulus, being shown to be applicable to all these cases: and a connexion has been established between the sound to be obtained from a given solid, and its strength in resisting a flexure of any kind; or, in the case of ice and water, between the sound in a solid and the compressibility in a fluid state. The doctrine of sound and of sounding bodies in general has also received some new illustrations, and the theory of music and of musical intervals has been particularly discussed.

The theory of the tides has been reduced into an extremely simple form, which appears to agree better with all the phenomena, than the more intricate calculations which they have commonly been supposed to require.

I have... attempted to throw some new light on the general properties of matter in other forms: and on the doctrine of heat, which is materially concerned in them; and to deduce some useful conclusions from a comparison of various experiments on the elasticity of , on evaporation, and on the indications of s.

A permanent alteration of form limits the strength of materials with regard to practical purposes, almost as much as fracture; since, in general, the force which is capable of producing this effect is sufficient, with a small addition, to increase it till fracture takes place.

With respect to the mathematical part of optics, the curvature of the images, formed by lenses and mirrors, has been correctly investigated, and the inaccuracy of some former estimations has been demonstrated.

have enumerated, in a compendious and systematical form, the principal facts which have been discovered with respect to galvanic electricity; and I have fortunately been able to profit by Mr. Davy's most important experiments, which have lately been communicated to the , and which have already given to this branch of science a much greater perfection, and a far greater extent, than it before possessed.

When I was a boy, I thought myself a man. Now that I am a man, I find myself a boy.

There is no study more difficult than that of physic: it exceeds, as a science, the comprehension of the human mind: and those who blunder onwards, without attempting to understand what they see, are often very nearly on a level with those, who depend too much on imperfect generalisations, applied to facts, which can scarcely be subjected to any well marked analogy. Hence it may happen, that talents and labour may become useless for want of a proper direction... To assist in furnishing the student with a sufficient direction... is the principal object of this work.

I have resolved to confine my studies and my pen to medical subjects only. For the talents which God has not given me, I am not responsible, but those which I possess, I have hitherto cultivated and employed as diligently as my opportunities have allowed me to do ; and I shall continue to apply them with assiduity, and in tranquillity, to that profession which has constantly been the ultimate object of all my labours.

Besides these improvements,... there are others,... which may... be interesting to those... engaged in those departments... Among these may be ranked, in the division of mechanics, properly so called, a simple demonstration of the law of the force by which a body revolves in an ellipsis; another of the properties of al pendulums; an examination of the mechanism of animal motions; a comparison of the measures and weights of different countries; and a convenient estimate of the effect of human labour: with respect to architecture, a simple method of drawing the outline of a column: an investigation of the best forms for arches; a determination of the curve which affords the greatest space for turning; considerations on the structure of the joints employed in carpentry, and on the firmness of wedges; and an easy mode of forming a kirb roof: for the purposes of machinery of different kinds, an arrangement of bars for obtaining rectilinear motion; an inquiry into the most eligible proportions of wheels and s; remarks on the friction of wheel work, and of balances; a mode of finding the form of a tooth for impelling a pallet without friction; a chronometer for measuring minute portions of time; a clock ; a calculation of the effect of temperature on steel springs; an easy determination of the best line of draught for a carriage; an investigation of the resistance to be overcome by a wheel or roller; and an estimation of the ultimate pressure produced by a blow.

In the department of , the phenomena of halos and parhelia have been explained, upon principles not entirely new, but long forgotten: the functions of the eye have been minutely examined, and the mode of its accommodation to the perception of objects at different distances ascertained: the various phenomena of coloured light have been copiously described, and accurately represented by coloured plates; and some new cases of the production of colours have been pointed out, and have been referred to the general law of double lights, by which a great variety of the experiments of former opticians have also been explained; and this law has been applied to the establishment of a theory of the nature of light, which satisfactorily removes almost every difficulty that has hitherto attended the subject.

It may hereafter be considered how far the excellent experiments of Count Rumford, which tend very greatly to weaken the evidence of the modern doctrine of heat, may be more or less favourable to one or the other system of light and colours.

The arrangement of the whole work is probably different... from any other... the extent of the subjects... rendered it necessary to preserve a... methodical and uniform system; and it is presumed, that this arrangement will be... of some value, especially in a work calculated to serve as a key, by means of which, access may be obtained to all the widely scattered treasures of science; and which will enable those... desirous of extending their researches in any particular department, to obtain expeditiously all the information that books can afford them.

The historical part of the work can scarcely be called new, but several of the circumstances, which are related, have escaped the notice of former writers on the history of the sciences.