360] PEC An n'osurd opinion prevails In some pcirt.-. of the country, that the sivnllo/i'ing nfpell'leg h conducive to health; and that such stones as- sist the stomach in digesting food. Tins praflice probably originated from the example of birds picking up gravel; an expedient which they instin6tively adopt, and ■with- out which their health becomes impaired. The stomach of man, however, is essentially different in its structure from that of the I'ea- thered tribe ; hehce such aids are altogether useless, nay hurtful to the comminution of food. — Al- though many persons may swallow even large pebbles for a series of years, with impunitxi ; yet this un- iiatural praftice can be produ(51ive ef no real beneiit ; and; as there are ca^ses on record, in which it has proved • fatal, the most judicious course will be to avoid so hazard- ens an experiment. PECTORALS, a term employed to express such medicines as are appropriated to the diseases of the chest and lungs. They are admi- nistered either with a view to allay an irritation prevailing in the organs of breathing: such are, liquorice, linseed-tea, mucilage of gum-arabic, &c. which may properly be called demulcents ; or, in order to pro- mote the expctioratio7i of tough and viscid mucus ; for instance, the roots of the rattle-snake, calaguala (vol. ii. p. 82), or similar drugs 3 the use of which, however, requires great precaution.— See Especto- EANTS. In obstinate coughs, which do not yield to the peSioral remedies commonly prescribed, we venture, from experience, to recommend the following mixture : Take tinc- ture of squill, end balsam of Co- paiba^ of each half an cunce ; and PED syrup of saffron, one ounce : let them be incor[)orated, and a tea- spoonful may be taken, according to circumstances, every hour or, oftencr. PEDOMETER, orPcDOMETER, a contrivance for measuring dis- tances, vhich is usually constru6ted in the form of a watch, and consists of several wheels with teeth, that are arranged in the same plane, and correspond with each other. Such instruments are either fastened by means of a string, chain, &c. to the knee of a person, or to the wheel of a carriage 5 and advance one notch at every step, or each revolution of the wheel: so that the number be- ing marked on a dial-plate, the tra- veller is enabled to compute his progress by the number of his steps, or to measure accurately the dis- tance between certain places. Some of these machines are contrived s.o as to mark both the time, and dis- tance ; by combining within the same case, the mechanism of a watch, so that they may be conve- niently worn in the pocket. The utility of pedometers for the purpose of surveying Land being obvious, various instruments of this description have been con- strufted by ingenious mechanics, in order to facilitate the practice of geometry. Among these, Mr. Edgewokth's late contrivance deserves to be first mentioned, on account of its great simplicity j but, as it is calculated only for level grounds, and is apt to be deranged by hilly or irregular surfaces, we decline to enter into any detail. A pedometer, upon a new plan, was a few years since contrived hy Mr. W. Eraser, mathematical in- strument-maker, of New ]5ond- sti-eet. It is stated to be perfectly corred^ and not liable to be out of order.
