LOCKER LOCOMOTION. 



509 



to which the Essay itself has mainly conduced, it will 

 ever prove a valuable guide in the acquirement of 

 the science of the human mind. His next great 

 work, his two Treatises on Government, was 

 opposed by the theorists of divine right and passive 

 obedience (see Legitimacy), and by writers of Jaco- 

 bitical tendencies ; but it upholds the great principles, 

 which may be deemed the constitutional doctrine of his 

 country. It was a favourite work with the statesmen 

 of the American revolution, by whom it is constantly 

 appealed to in their constitutional arguments. His 

 Reasonableness of Christianity maintains, that there 

 is nothing contained in revealed religion inconsistent 

 with reason, and that it is only necessary to believe that 

 Jesus is the Messiah. His posthumous works, also, 

 have caused him to be considered, by some, as a Soci- 

 nian. Besides the works already mentioned,Locke left 

 several M3S. behind him, from which his executors, 

 Sir Peter King and Mr Anthony Collins, published, 

 in 1706, his Paraphrase and Notes upon St Paul's 

 Epistles to the Galatians, Corinthians, Romans, and 

 Ephesians, with an Essay prefixed for the Under- 

 standing of St Paul's Epistles, by a reference to St 

 Paul himself. In 1706, the same parties published 

 Posthumous Works of Mr Locke (8vo), comprising 

 a Treatise on the Conduct of the Understanding, an 

 Examination of Malebranche's Opinion of seeing all 

 Things in God. His works have been collected 

 together, and frequently printed in 3 vols. folio, 4 

 vols. quarto, and, more lately, in ten vols, 8vo, with 

 a life prefixed, by Law, bishop of Carlisle. Some 

 unpublished MSS. yet remain in possession of lord 

 King, who has given to the public some valuable 

 materials in his Life and Correspondence of John 

 Locke (London, 1829). See, also, Stewart's Philo- 

 sophical Essays. 



LOCKER ; a kind of box, or chest, made along 

 the side of a ship, to put or stow anything in. 



Shot-lockers ; strong frames of plank near the 

 pump-well in the hold, in which the shot is put. 



LOCKMAN. See Lokman, and Fable. 



LOCOMOTION. The arts of locomotion are very 

 well described in Bigelow's Technology (Boston, 

 1829), and the few remarks that follow are abridged 

 from the first part of the article. The chief obsta- 

 cles which oppose locomotion, or change of place, 

 are gravity and friction, the last of which is, in most 

 cases, a consequence of the first. Gravity confines 

 all terrestrial bodies against the surface of the 

 earth, with a force proportionate to the quantity of 

 matter which composes them. Most kinds of 

 mechanism, both natural and artificial, which assist 

 locomotion, are arrangements for obviating the 

 effects of gravity and friction. Animals that walk, 

 obviate friction by substituting points of their bodies 

 instead of large surfaces, and upon these points they 

 turn, as upon centres, for the length of each step, 

 raising themselves wholly or partly from the ground 

 in successive arcs, instead of drawing themselves 

 along the surface. As the feet move in separate 

 lines, the body has also a lateral, vibratory motion. 

 A man, in walking, puts down one foot before the 

 other is raised, but not in running. Quadrupeds, in 

 walking, have three feet upon the ground for most of 

 the time ; in trotting, only two. Animals which 

 walk against gravity, as the common fly, the tree- 

 toad, &c., support themselves by suction, using 

 cavities on the under side of their feet, which they 

 enlarge, at pleasure, till the pressure of the atmo- 

 sphere causes them to adhere. In other respects 

 their locomotion is effected like that of other walk- 

 ing animals. Birds perform the motion of flying by 

 striking the air with the broad surface of their wings 

 in a downward and backward direction, thus propel- 

 ling the body upward and forward. After each 



stroke, the wings are contracted, or slightly turned, 

 to lessen their resistance to the atmosphere, then 

 raised, and spread anew. The downward stroke 

 also, being more sudden than the upward, is more 

 resisted by the atmosphere. The tail of birds 

 serves as a rudder to direct the course upward or 

 downward. When a bird sails in the air without 

 moving the wings, it is done in some cases by the 

 velocity previously acquired, and an oblique direction 

 of the wings upward; in others, by a gradual de- 

 scent, with the wings slightly turned, in an oblique 

 direction, downward. Fishes, in swimming fonvard, 

 are propelled chiefly by strokes of the tail, the 

 extremity of which being bent in an oblique posi- 

 tion, propels the body forward and laterally at ti'e 

 same time. The lateral motion is corrected by the 

 next stroke, in the opposite direction, while the 

 forward course continues. The fins serve partly to 

 assist in swimming, but chiefly to balance the body, 

 or keep it upright ; for, the centre of gravity being 

 nearest the back, a fish turns over, when it is dead 

 or disabled.* Some other aquatic animals, as 

 leeches, swim with a sinuous or undulating motion 

 of the body, in which several parts at once are made 

 to act obliquely against the water. Serpents, in like 

 manner, advance by means of the winding or serpen- 

 tine direction which they give to their bodies, and by 

 which a succession of oblique forces are brought to 

 act against the ground. Sir Everard Home is of 

 opinion that serpents use their ribs in the manner 

 of legs, and propel the body forwards by bringing 

 the plates on the under surface of the body to act, 

 successively, like feet against the ground. This he 

 deduces from the anatomy of the animal, and from 

 the movements which he perceived in suffering a 

 large coluber to crawl over his hand. Some worms 

 and larvae of slow motion, extend a part of their 

 body forwards, and draw up the rest to overtake it, 

 some performing this motion in a direct line, others 

 in curves. When land animals swim in water, they 

 are supported, because their whole weight, with the 

 lungs expanded with air, is less than that of an equal 

 bulk of water. The head, however, or a part of it, 

 must be kept above water, to enable the animal 

 to breathe ; and to effect this, and also to make pro- 

 gress in the water, the limbs are exerted, in succes- 

 sive impulses, against the fluid. Quadrupeds and 

 birds swim with less eflbrt than man, because the 

 weight of the head, which is carried above the 

 water, is, in them, a smaller proportional part of 

 the whole than it is in man. All animals are pro- 

 vided, by nature, with organs of locomotion best 

 adapted to their structure and situation ; and it is 

 probable that no animal, man not being excepted, 

 can exert his strength more advantageously by any 

 other than the natural mode, in moving himself over 

 the common surface of the ground.f Thus walking 

 cars, velocipedes, &c., although they may enable a 

 man to increase his velocity, in favourable situations, 

 for a short time, yet they actually require an increased 

 expenditure of power, for the purpose of transporting 

 the machine made use of, in addition to the weight 

 of the body. When, however, a great additional 

 load is to be transported with the body, a man, or 

 animal, may derive much assistance from mechanical 

 arrangements. For moving weights over the com- 

 mon ground, with its ordinary asperities and ine- 



* The swimming-bladder, which exists in most fishes, 

 though not in all, is supposed to have an agency in 

 adapting the specific gravity of tin- figh to the particular 

 depth in which it resides. The power of the animal to 

 rise or sink, by altering the dimensions of this organ, has 

 been, with some reason, disputed. 



t This remark, of course, does not apply to situations in 

 which friction is obviated, as upon water, ice, rail-roads, 

 &c. 



