237 



THRESHING. 



THUG. 



238 



7 pence bear to 14 applea : simply because 5 pence are not any assign- 

 able fraction of 10 apples. That there is a relation is true ; but that 

 relation is not proportion. Thus, it is not absurd to say, in the 

 common language of the rule, As 5 pence are to 10 apples, so are 

 7 pence to 14 apples; for the first does stand to the second in the 

 same relation as the third to the fourth : 5 pence must, at all rates, do 

 as much towards the purchase of 10 apples as 7 pence towards that of 

 14 apples. With this understanding, there is no objection to the common 

 mode of statement, and the proof of the rule is as follows : If A of the 

 first produce B of the second, then, at the same rate of production, 1 of 



the first must produce 2 of the second ; whence c of the first must 



produce c x _, or of the second. 



The importance of the rule of three induced arithmeticians to 

 attach two other rules to it : the inverse rule of three (called by 

 Recorde, Baker, &c., the backer rule) ; and the double rule of three. 

 Some of the writers of Cocker's school, 'apparently by an abbreviation 

 of his words, tells us that the rule of three inverse is used " when less 

 requires more and more requires less ; " meaning that the greater the 

 third of the given numbers, the less will be the answer, and rice vend. 

 Thus, suppose that 10/. has been lent me for 3 months, and I want to 

 know how long I ought to lend a given sum (other than 10?.) in return : 

 evidently the more I lend, the less the time for which I ought to lend 

 it. If the sum be 15?., then 3 months is to the time required, not as 

 10 to 15, but in its inverse ratio, as 15 to 10, or 15 : 10 : : 3 : 3x10^-15, 

 or 2 ; and 2 months is the answer required. 



The double rule of three (at least in the class of questions which 

 are usually considered as falling under it) is applied where time is an 

 element in the production which the question supposes. For example : 

 supposing it known that A men can pave B square feet in c days, it 

 may be asked how many men can pave l> square feet in e days, or how 

 many square feet can a men pave in c days, or how many days will it 

 take a men to pave 6 square feet. If we write down the data and 

 answer in two lines, and in the following order force employed effect 

 produced time of production thus : 



A 



a 



the rule is Take such an answer as will make the extremes of each 

 line multiplied by the mean of the other, the same in both. That is, 

 let A'XJ= HBC, and according as a, 6, or e, is to be found, the mode of 

 working is as follows : 



A&c OBC Aic 



0= "Si"' 6 = 1i>' e = "S"- 



V B 



The proof is as follows: One man in c days could pave - square 



B 



feet, and in one day square feet. By similar reasoning one man in 



b 

 one day could pave square feet. Hence 



B 



- 



J 



-; 



The principal caution which a beginner requires is, not to suppose 

 that the rule of three (or the rule of finding a fourth quantity which, 

 which three others, shall constitute a proportion) is to be applied in all 

 can* in which three quantities are given to find a fourth. That such 

 a caution in necessary arises from the defect of works on arithmetic, 

 which frequently exhibit this rule without any mention of proportion, 

 and leave it to be inferred that there is but one way of obtaining a 

 fourth quantity from three others. 



THRESHING. The separation of the grain from the ear in com 

 has always been one of the most laborious operations on a farm. 

 Whi-n- the quantity grown is merely sufficient to supply food for the 

 cultivators of the soil, the simplest methods answer the purpose suffi- 

 ciently. The corn, taken by handf uls, may be beaten on a piece of 

 wood or a table, and by repeatedly turning the straw the whole of the 

 grain may be readily beaten out. This mode of threshing may be still 

 adopted in order to obtain the finest and ripest grains for seed ; but 

 then the straw is afterwards threshed over again with the Jtail. 



Where the corn is threshed out immediately after harvest, to be put 

 into a granary, aa is the ease in those countries where extensive tracts 

 of rich land are sown with corn two or three times without much 

 tillage or manuring, and then left to be recruited by several years' rest 

 and pasture, the most common practice is to level a portion of a field, 

 and, laying the corn in the straw in a large circle, to drive oxen and 

 horses over it till it is all trodden out. This is the method alluded to 

 in Scripture, and can only take place where the climate is serene and 

 dry. Till ingenuity had produced machines to supersede the flail, this 

 wan the only instrument in use. The first idea of a machine for 

 HIM Ailing was that of imitating the motion of the flail; but so much 

 clci* m!-< i m the eye of the thresher, that no mechanism could well 

 imitate the motion of his arms. The present improved threshing- 

 machine ia now so common that it will suffice to give the general 



jrinciple of action. A rapid motion is given to a hollow cylinder 

 round a horizontal axis ; on the outer surface there are projecting ribs 

 parallel to the axis at equal distances from each other ; the width of 

 ;hese is from two to six inches. Around half the cylinder is a case, 

 ;he inner surface of which is lined with plates of cast-iron grooved in 

 ;he direction of the axis. The ribs or beaters come quite close to these 

 rooves, so that an ear of wheat or other corn cannot well pass between 

 them without being flattened. The sheaves of corn, having been 

 untied, are spread on a slanting table, and in some machines are drawn 

 in between two iron rollers, of which one is plain and the other fluted. 

 The motion of these rollers is slow, while that of the cylinder or drum 

 is rapid. The beaters act on the straw as it comes through, and beat 

 out most of the corn ; but what remains is carried in between the 

 beaters and the fluted case, and when it has made half a revolution all 

 the grain has been beaten and rubbed out. It falls on a shaker which 

 lets the grain through, but tosses off the straw. Moveable threshing- 

 machines are very generally in use in England. The price of threshing 

 in this way is about half of what is usually paid for threshing with the 

 flail ; it is more rapidly done, there is less chance of pilfering, and 

 fewer grains remain in the straw. 



On very large farms it has been found economical to erect a steam- 

 engine to work the threshing-machine, chaff-cutter, and other domestic 

 implements. But travelling machines thresh out much the largest 

 quantity of the corn that is grown in England. The moveable steani- 

 engines which are used for working such machines are now made in 

 immense numbers, and no doubt 1 5,000 to 20,000 horse-power is thus 

 every year added to the forces used in agriculture. 



THROMBUS is a tumour formed by blood effused from a vein after 

 bleeding, and coagulated in the adjacent cellular tissue. It is a kind 

 of intense ecchymosis or bruise, and usually arises from the puncture 

 in the vein not having been made exactly opposite that in the skin, so 

 that some of the blood, instead of flowing out, is infiltrated between 

 the vein and the surface. It is rarely of sufficient importance to 

 require treatment, and is usually removed like the effused blood 

 of an ordinary bruise. Sometimes, however, inflammation ensues 

 around the tumour, which should be treated by leeches and cold ; 

 or, if it proceed to suppuration, should be managed like a common 

 abscess. 



THRUSH or APHTHAE is a disease to which young children 

 are particularly liable. It is a disease of the mucous membrane of 

 the mouth and fauces, and manifests itself in the form of small 

 points, rings, conical or hemispherical elevations. These some- 

 times increase in size, and become large spots, which arc' 

 covered with a membrane of milk or pearl-white colour passing 

 into a gray or yellowish colour. This membranous matter is of a 

 more or less soft consistence, and varies, in thickness. It is at first 

 firmly adherent to the mucous membrane, but eventually peels off, 

 leaving the mucous membrane uninjured. These spots are found on 

 the inner edge of the lips, on the cheek, the gums and the palate ; on 

 the upper and lower surface of the tongue, in the throat, and in the 

 oesophagus down to the stomach. 



On placing this membranous secretion under the microscope, it is 

 found to consist of epithelial cells, a certain amount of exuded matter, 

 and of the JUaments and tpores of a fungus known by the name of 

 Outturn albicam. [ENTOPHYTA'J OIDICM, in NAT. HIST. Div.] 



The filaments of the fungus are cylindrical, elongated, straight, or 

 curved and tubular. The interior of the tube is transparent. In the 

 midst of these filaments are found minute bodies composed of two to 

 four oval cells. These are the germinating spores from which originate 

 the true spores ; which lie together frequently in masses and vary in 

 number according to the age of the fungus. 



There is no doubt that thrush entirely depends on the presence of 

 this fungus. It appears, however, that certain states of the system 

 invite their attacks. When children are weakly or have been subject 

 to derangement of the bowels from any cause, the fungus appears to 

 find a fit nidus for its development. In some cases the irritation pro- 

 duced by the fungus engenders inflammation which ends in ulceration, 

 and this may spread and even produce destructive effects. 



Old people as well as children are subject to attacks of the same 

 fungus when the conditions are present which invite their attacks. 

 Such being the nature of thrush, it is very clear that it is not critical 

 of any general state of the system. 



Thrush is often confounded with various affections of the mouth, 

 such as idiopathic inflammation with ulceration, accumulation of 

 epithelial cells, the fur of the tongue, and the remains of food 

 especially milk, from all of which it may be easily distinguished by the 

 presence of the filaments and spores of the fungus. 



In the treatment, the object should be to destroy the fungus by 

 external application, and to rectify the diseased condition of the child. 

 A dilute solution of nitrate of silver painted over the aphthous spots 

 has been found useful as an external application. Acidity of the 

 stomach and bowels may be corrected by the carbonates of potash, 

 magnesia, or soda. The preparations of iron with cod-liver oil arc 

 amongst the best remedies for the constitutional state in which thrash 

 occurs. 



(Kiichemeister On Animal and Vegetable Parasites, translated by 

 Dr. Lankester.) 

 TIIUQ (from Hindustanee (hvjna,, to deceive) means a deceiver, 



