C H A 



Network, frame. Two cords may be attached to the wheel at B, 

 **"" "V^"^ and passing round it in opposite directions, will move 

 f. A " the vibrating frame. From the smaller part of this bar- 

 Fig.8,9,10, rel or cylinder at A, two similar cords will complete 

 11, 12. ' ' the connection with the treddles 1 and 2. Thus the 

 depression of the treddle 1 will produce one motion, 

 and that of the treddle 2 will in like manner give the 

 inverted one. Fig. 9. is a profile of the same appa- 

 ratus. Figures 10. and 11. exhibit two different ways 

 of giving motion to the cross rails and pins for chan- 

 ging the mesh. In Fig. 10. this is done by a band pas- 

 sing over a pulley. In Fig. 11. the oame is done by 

 two inverted racks, and an intermediate pinion. The 

 first of these will be the cheapest plan of construction, 

 but the second is by much the most steady and certain 

 in its operation. Fig. 12. is a plan for shifting the 

 receiving beam to wind up the finished net. It is done 

 merely by pulling a handle at A, a weight (not repre- 

 sented) being suspended from the other extremity B 

 of the cord. 



Some idea of the nature of the machine may be 

 collected from these drawings. With regard to the 

 expence of the construction, the writer intended to 

 conclude this description with an estimate ; but upon 

 reflection he has been induced to postpone this, at 

 least for the present, for the following reasons. 



1st, For two very conclusive and unavoidable rea- 

 sons ; the first trial of every mechanical experiment 

 is conducted at a much greater expence than what 

 becomes necessary in a more advanced stage. It is 

 hardly to be expected that any projector, however 

 conversant he may be both with the theory and 

 practice of mechanics, can at once arrange and ma- 

 ture a complicated and extensive body of machinery, 

 so as both to give it the greatest possible efficiency, 

 and construct it with the strictest attention to simpli- 

 city and economy. It is perhaps as much as ever 

 has been effected in new machinery, if the advantage 

 gained by its adoption be sufficient to counterbalance 

 the difficulties to which it is exposed, and leave an 

 ultimate profit in its favour. Hence projectors very 

 frequently, from forming expectations more sanguine 

 than reason will warrant, are apt to involve both 

 themselves and others in disappointments, the more 

 severe in proportion to the expectations which have 

 been excited. But were the engineer capable of even 

 much greater precision in all the minutiae of his plan 

 than is generally found to be the case, it would still 

 be impossible that he could conduct his first experi- 

 ments upon terms nearly equal to those which may 

 be obtained afterwards. Every operative mechanic 

 whom he may have occasion to employ, must have a 

 considerable practice before he can execute his work 

 either so perfectly or so speedily as in matured busi- 

 nesses. It is also impossible to allot or apportion 

 the various departments of the work in that order 

 and method necessary to produce that division of la- 

 bour which is the very essence of every business. Up- 

 on the whole, perhaps the most economical plan is 

 merely to try the experiment upon a very limited 

 scale for some time, and thus to purchase that expe- 

 rience which must be purchased at aa small an expence 

 as possible, (j. D. ) 



CHALCEDONY. See ORYCTOGNOSY. 

 CHALDEA. See BABYLON. 

 CHALK. See ORYI TOGNOSY. 

 CHALLENGE, (Calumnia,) is generally ua- 



C H A 



derstood, in common language, to signify a. summons Challenge, 

 or provocation to fight a duel, in consequence of an v "" > "Y*"" 

 affront offered in derogation of honour. This is con- 

 sidered, in law, as an offence against the peace ; and, 

 therefore, to send a verbal or written challenge,- or to 

 be the bearer of it, are punishable by fine and im- 

 prisonment, according to circumstances. The mere- 

 ly endeavouring to provoke another to send a chal- 

 lenge is also deemed a high offence ; and if the chal- 

 lenge, arise on account of money won by gaming, the 

 offender, by Stat. 9 Ann. c. 14. shall forfeit all his 

 goods to the crown, and suffer two years imprison- 

 ment. The Court of King's Bench frequently 

 grant informations against persons sending challenges 

 to justices of the peace, and in other heinous cases. 

 See DUEL. 



Challenge is also a legal term, and generally sig- 

 nifies an exception taken against jurors, who are re- 

 turned by the sheriff to pass on a trial. Challenges 

 to jurors, in civil cases, are of two sorts, challenges 

 to the array, and challenges to the polls. Challenges 

 to the array are an exception at once to the whole 

 panel, in which the jury are arrayed by the sheriff in 

 his return, and may be made upon account of par- 

 tiality, or some default in the sheriff or his under of- 

 ficer. Although there should be no personal objec- 

 tion against the sheriff, yet it is a good ground of 

 challenge to the array, if he arrays the panel at the 

 nomination, or under the direction of either party. 

 Challenges to the polls are exceptions to particular 

 jurors, and are made, 1. Propter honoris respectum; 

 as if a lord of parliament be impanelled on a jury, he 

 may be challenged by either party, or may challenge 

 himself. 2. Propter defectum, on account of a sus- 

 picion of biass or partiality. Tina may be either a 

 principal challenge, or to the favour. A principal 

 challenge is when the cause assigned carries with it 

 prima facie evident marks of suspicion : Challenges 

 to thefavour, on the other hand, are when only pro- 

 bable circumstances of suspicion are assigned, the 

 validity of which is left to the determination of triors t 

 who are two indifferent persons named by the court. 

 4. Propter delictum, on account of some crime or 

 misdemeanour, which affects the person's credit, and 

 renders him infamous. 



Challenges upon any of the foregoing accounts are 

 stiled challenges for cause; and they may be made 

 without limitation in both civil and criminal trials. 

 But in trials for felony, the English law, infavorem 

 vitce, allows the prisoner a peremptory challenge to 

 a certain number of jurors, without shewing any 

 cause at all. By stat. 22 Hen. VIII. c. 14. the num- 

 ber of peremptory challenges is limited to twenty. 

 This privilege of peremptory challenges is denied to 

 the king, by stat. 33 Edw. I. st. 4. It is held, how- 

 ever, that the king need not assign his cause of chal- 

 lenge, till all the panel is gone through, and unless 

 there cannot be a full jury, without the persons so 

 challenged j in which case the king's counsel must 

 shew cause, otherwise the juror shall be sworn. In 

 cases of high treason, the prisoner may, by stat. 

 7 W. III. peremptorily challenge thirty -five jurors. 



Members of a court martial may be challenged by 

 the prisoner on the score of partiality. The prisoner, 

 however, must assign his cause of challenge, of the 

 relevancy, propriety, and validity of which the mem- 

 bers are themselves the judges. This privilege of 



