Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 3, 1802).djvu/108

9o] LEV M-ceded J and, as the Blnck Cos- Lettuce grows large, it will be ne- cessary to tie its leaves together, in order to whiten the inner part. There are two otiier sorts, known under the name of Dutch brown and Green Cupiich'nt Lettuce, which may be sown late, under walls 5 being very hardy, they withstand the severity of the winter, and will be valuable when no other green salad can be procured. — Bechstein states a curious faft, vhich deserves to be recorded, namely, if the two varieties last mentioned be planted together, and suftered to bear seeds, in a rich, warm, but moist soil, the future produce of such seed will be a new and very excellent kind of this plant, forming extraordinary large heads, the leaves of which are sprinkled with deep red spots, and uncommonly tender. Properties : — ^The various kinds of garden-lettuce are emollient, cooling, and wholesome salad- herbs ; they are easy of digestion, somewhat aperient, and supposed to possess a soporific quality : there is no doubt, that by abating heat, and relaxing the fibres, they in many instances contribute to pro- cure rest. But, for this purpose, lettuces should not be eaten with oil and vinegar, as the former ren- ders them less digestible j but, if either or botli of those condiments must be used, it vvill be advisable to add sugar, which v.ill counteraft the rancid nature of the oil : though .simple salt is the most proper spice for salads. Lettuce, the Hair. See Com- mon Sow-Thistle. LEVEL, an instmment by means of which a line may be drawn pa- rallel to the horizon, in order tp determine the height of one place LEV •« ith respe6t to another ; for laying^ grounds even, conduding water, regulating descents, draining fens, &:c. There are various kinds of levels, adapted to dilferent purposes, of which we shall notice only such as are of a simple construction, and in general use. 1 . The Carpenters' aild Paviors' Level consists of a long ruler, in the centre of which is fixed, at right angles, another somewhat larger, and at the top of which is fastened a line, that shews the base to be horizontal. 2. The Masons' Level is composed of three rules, so joined as to form a redangie, somewhat similar to die letter A ; from the top of which a plummet is suspended, by means of a thread that passes over a pcr- pjendicular line marked in the mid- dle of the base, if the objeft to Avhich the level is applied be hori- zontal ; but which deviates from such mark, in case one side be lower than the other. 3. The Water Level, which shews the horizontal line by means of water or any other fluid, is founded on the principle that water is always level. Ihe most simple instruments of this kind are made of a long wooden trough or canal, the sides of which are parallel to the base ; so that, when it is equally filled with water, its surface points out the aclual degree of declivity. Or, it may be made with two cups fitted to each end of a pipe, three or four feet long, and about one inch in diameter, so that the water may communicate from one cup to the other : and, as this pipe is nioveable on its stand, by means of a ball or socket, when the two cups become equally filled with water, their surfaces shew the hhe of