FRU1TFULNESS FUEL. 



329 



obliged to use in the society. The German language, 

 although their efforts were in a great measure unsuc- 

 cessful, yet owes much to them. Some of the words 

 first formed by this society, as, for instance, gegen- 

 stand (object), have passed into the language, while 

 others, formed at the same time, as unterstand (sub- 

 ject), have never come into use. The society con- 

 tinued down to 1680, and had always a sovereign for 

 its president, There was a good deal of pedantry 

 attending it. 



FRUITFULNESS ; the power of abundant pro- 

 duction. This power exists in some organic beings 

 in an incredible degree : in a poppy, 32,000 seeds 

 have been counted. The elm produces annually 

 100,000 seeds. How numerous is the annual pro- 

 duction of seeds from fruit-trees, &c.! As each of 

 these seeds is capable of becoming an individual of 

 the same sort, if each of them grew up, the whole 

 surface of the earth would soon be covered with these 

 trees. In the lower classes of animals, the fruit- 

 fulness is no less great: the queen-bee lays every 

 year 5000 or 6000 eggs. The vast swarms of locusts, 

 which sometimes lay waste immense tracts of culti- 

 vated country in Asia and Africa, justify us in attri- 

 buting to them the greatest fruitfulness. 



The smallest herring has 10,000 eggs. A carp 

 which weighs only half a pound, has 100,000, a 

 larger one, 262,280 ; a perch, 324,640. The spawn 

 of the sturgeon is calculated to contain 7,653,200 

 eggs. In the cod-fish, the number of eggs is reck- 

 oned at 9,344,000. In the higher classes of animals, 

 there is less of fruitfulness ; yet even in men, it is 

 greater than the mortality. In the last case, how- 

 ever, much depends upon climate, season, food, 

 habits, manners, temperament, &c. 



FRUSTUM, in mathematics ; a part of some solid 

 body separated from the rest. The frustum of a 

 cone is the part that remains, when the top is cut 

 off by a plane parallel to the base, and is otherwise 

 called a truncated cone. The frustum of a pyramid 

 is also what remains, after the top is cut off by a 

 plane parallel to its base. 



FUCI; a family of cryptogamic plants, inhabiting, 

 exclusively, the ocean, and generally known by the 

 name of sea-weed. The substance of these vegeta- 

 bles is coriaceous, membranaceous, or cartilaginous, 

 hardening when dried, and becoming sometime 

 brittle. They are generally branched, or furnished 

 with fronds, having the form of leaflets, but some- 

 times simple, or filiform. Their branches are fre 

 quently provided with prominent air vesicles, anc 

 terminated with pod-like protuberances, some con- 

 taining interlaced hairs, and others a gelatinous 

 matter enveloping minute globules which are re- 

 garded as the seeds ; but the origin and functions o: 

 these organs are not well understood ; and many /we 

 are destitute of them. Several species present at cer- 

 tain seasons little tufts of articulated hairs, which, on 

 falling, leave little points on the surface of the fronds 

 Some fuci are transparent, but their colour is usually 

 brown, with a greenish or reddish tinge ; and, al 

 though varying so much in form, they may be recog 

 nised by a certain family resemblance. Their inter 

 nal structure is entirely cellular, consisting of cells 

 either rounded or more or less elongated ; and nutri 

 tion takes place by absorption from the whole sur 

 lace : when partially submerged in water, the portion 

 exposed to the air dries up, while the remainde 

 continues to vegetate. Some species are almos 

 microscopic, while others, inhabiting, especially, tin 

 South seas, attain the length of several hundred feet 

 Their duration is not well ascertained, but usuall 

 they are perennial. Very few, if any, are parasitic 

 though great numbers of polypi and algte are often 

 attached to them. They are usually fixed by on 



ixtremity to rocks, stones, &c., and rocky coasts are 

 requently covered with them from above low-water 

 mark, as far as the eye can discern the bottom of the 

 jcean. Some, however, are entirely free, and vege- 

 ,ate as well as those which are attached : of this kind 

 s the/ucus natans, which has multiplied prodigiously 

 aetween the tropics, forming floating masses, that 

 ;over extensive portions of the ocean, and are so 

 dense as to impede the course of ships, at the same 

 .ime serving as a retreat for immense numbers of 

 fish, shells, worms, and Crustacea, affording an ali- 

 ment to these various animals, and even to man, 

 though this latter fact is but little known. The na- 

 ;ives of New Holland broil the F. palmatus, and use 

 t for food ; and the same species is eaten both in 

 Scotland and Ireland, either fresh as a salad, or more 

 requently, after being dried and rolled, it is chewed 

 ike tobacco. Some species are highly esteemed in 

 India, and the swallows' nests, so celebrated through- 

 out the East Indies, consist, according to some 

 writers, only of fuci in a state of partial decomposi- 

 tion. On some parts of the coast of Europe, the 

 fuci are cut several times a year, either for manure, 

 or for burning, to obtain the soda contained in their 

 ashes. For this latter purpose, they are dried as 

 quickly as possible, placed in a pit five or six feet 

 deep, containing a few sticks at the bottom, which, 

 when the pit is filled, are set on fire, and the whole 

 is burnt as slowly as possible without producing 

 flame. Besides soda, the ashes of fuci contain iodine. 

 FUEL. Doctor Black divides fuels into five 

 classes. The first comprehends the fluid inflammable 

 bodies ; the second, peat or turf; the third, charcoal 

 of wood ; the fourth, pit-coal charred ; and the fifth, 

 wood, or pit-coal, in a crude state, and capable of 

 yielding a copious and bright flame. The fluid in- 

 flammables are considered as distinct from the solid, 

 on this account, that they are capable of burning 

 upon a wick, and become in this way the most man- 

 ageable sources of heat; though, on account of their 

 price, they are never employed for producing it in 

 great quantities, and are only used when a gentle 

 degree, or a small quantity of heat, is sufficient. The 

 species which belong to this class are alcohol and 

 different oils. The first of these, alcohol, when pure 

 and free of water, is as convenient and manageable 

 a fuel for producing moderate or gentle heats as can 

 be desired. Its flame is perfectly clean, and free 

 from any kind of soot ; it can easily be made to burn 

 slower or faster, and to produce less or more heat, 

 by changing the size or number of the wicks upon 

 which it burns ; for, as long as these are fed with 

 spirit, in a proper manner, they continue to yield 

 flame of precisely the same strength. The cotton, 

 or other materials, of which the wick is composed, is 

 not scorched or consumed in the least, because the 

 spirit with which it is constantly soaked is incapable 

 of becoming hotter than 174 Fahrenheit, which is 

 considerably below the heat of boiling water. It is 

 only the vapour that arises from it which is hotter, 

 and this, too, only in its outer parts, that are most 

 remote from the wick, and where only the combustion 

 is going on, in consequence of communication and 

 contact with the air. At the same time, as the al- 

 cohol is totally volatile, it does not leave any fixed 

 matter, which, by being accumulated on the wick, 

 might render it foul, and fill up its pores. The wick, 

 therefore, continues to imbibe the spirit as freely, 

 after some time, as it did at the first. These are 

 the qualities of alcohol as a fuel. But these qualities 

 belong only to a spirit that is very pure. If it be 

 weak, and contain water, the water does not evapor- 

 ate so fast from the wick as the more spirituous part ; 

 and the wick becomes, after some time, so much 

 soaked with water, that it does not imbibe the spirit 



