11 E M 



REM 



ufed for pallets in feveral indaiices, we may proceed to ex- 

 plain the aftion of the difFcreiit parts, and to fliew how they 

 produce the defircd efFedts of producing equable impuUes 

 on the balance at all times, and of effecting certain and 

 fecure locking of the remontoir-fpring. In the figure 

 before us, tooth i of the wheel has juft proceeded far enough, 

 by the a6liou of the main-fpring and train, to wind up the 

 remontoir-fpring, and its detent N, urged by its own ipiral 

 Iprnig againft the curved face of the feAoral piece, fifler 

 Hiding finoothly along it, has locked it ; that is, by oppofing 

 it at right angles, prevents its return, which would take 

 place when the wheel leaves the arm M, or, which is the 

 fame thing, when the remontoir-fpring, on the fair.e arbor 

 with this arm, is wound up. The balance is now fuppofed 

 to have commenced its motion, carrying tlse pallets K and I 

 outwards from the wheel, but the fmall pallet I lias not 

 yet arrived at the flender fpring of the rcmontoir detent, 

 though it is Approaching it ; the flender fpring, however, 

 foon yields to the outward inipulfe of this fmall pallet, 

 without difturbing its arm or the detent N, therefore the 

 remontoir-fpring remains locked : at the return of the ba- 

 lance, which takes place when its fpnng is wound up, the 

 faid httle pallet I difplaces not only the flender fpring but its 

 arm alfo, which lies next towards the wheel, the one not 

 being liable to move in this inward dire£lion without the 

 other ; the confeque;-;ce is, that the detent N is now lifted 

 by its connedtion with the arm of the flender fpring, and at 

 that inilant the remontoir-fpring, being wound up, and at 

 liberty to aft, throws back the feftoral piece Q nearly its 

 whole breadth, but not quite, for the claw of the detent in 

 queftion refts on the curve of the fuftor during the motion 

 we have defcribed, till the unlocking lever O llrikes the 

 end of the fingle detent-fpring d, and forces the ruby pallet 

 1 out of the wheel, which wheel inllanlaneoufly relumes its 

 motion from the train, and meeting with lever M winds up 

 the remontoir-fpring a fecond time ; in the mean time the 

 impelling lever L has given its impulfe to the pallet or lever 

 K, and confequently to the balance, which has tnus had its 

 momentum increaled ; and en its returning vibration ex- 

 aftly the fame procefs is repeated. Thus the force of the 

 mamtaining power is expended in winding up at each alter- 

 nate ofcillation the remontoir-fpring, which fpring, fo re- 

 inforced, impels the balance in its turn by quantities of force 

 that are always the fame, whatever may be the irregularities 

 of the force tranfniitted through the train that winds up 

 the remontoir-fpring ; therefore, properly fpeaking, the 

 remontoir-fpring is the maintaining power that reftores, at 

 each alternate ofcillation, the lofs of momentum that the 

 balance has experienced from the refiftance of the air, and 

 friftion of the parts in aftion. This efcapement is, notwith- 

 ftanding, of the detached kind, feeing the balance performs 

 the greateft part of its ofciUations without any conneftion 

 of even the auxiliary force derived at intervals from the 

 remontoir-fpring ; and a chronometer of this conftruftion, 

 made by Hardy for his royal highnefs the duke of Suflex, 

 anfwers the maker's moft fanguine expeftation, and will 

 probably become a model for other makers when its merit 

 is proved, and made public. The fame artift has made 

 feveral experiments on the fame principle, with this differ- 

 ence, that the remontoir-lpring is retained by the lever reft- 

 ing Oil the tooth of the wheel, in place of being locked by 

 the feftoral piece, as in the one before us. 



Befides the preceding efcapement, Hardy invented one 

 for the aftronomical clock he made for the Royal Obfer- 

 vatory at Greenwich, which at firit fight appears to refera- 

 ble Mafley's and Prior's improved one, with fpring pallets, 

 but on clofe examination we difcovered that it has the fol- 



lowing defirable properties peculiar to itfelf; irt, it gn-ct 

 the impulfe not only from remontoir-fprings, but flrikcs and 

 unlocks the two feparate detents alternately, at the inttatit 

 when the pendulum has the grealejt velucity ; and, zdly, tlit 

 accelerating and retarding power imparted to the' pendulum 

 co-operates with the force of gravity, thereby deranging the 

 natural law of gravity as little as polfible. V?c feel not at 

 liberty to enter more minutely into the d&fcription of this 

 efcapement, becaufe we underltand its inventor propofes 

 giving an account of his machine liimfelf, to be read before 

 the Royal Society, as conftituting the compai-ion to Trough- 

 ton's tranfit circle, already defcribsd by the allronomcr 

 royal. We have permillion, however, to fubjoin the rate of 

 the clock in quellion for three quarters of a year, as taken 

 at the Roya! Obfervatory, which will afford the beft proof of 

 its pretenlions to public notice. We have further to add, that 

 the inventor has applied the fame principle of movement to a 

 chronometer of a large fize, in which the balance has two 

 metalHc rods to adjuit it for temperature, in place of the 

 metal being fluxed on the rim of the balance, as is common. 

 See Compensation. 



Trial of Mr. Hardy's clock at the Royal Obfervatory at 

 Greenwich in the vear 1 8 1 1 . 



From the above ftated authentic document it appears, that 

 for the nine months of trial, and in oppofite extremes of 

 temperature, the daily rate never varied quite four-Uriths of 

 a fecond ; and when the quantity of mercury proper for the 

 compenfation of the pendulum is exaftly afcertained, it may 

 be expected that the performance will be ftill more accurate ; 

 feeing that the deviation in the rate depends evidently on 

 the change of temperature, and not on the efcapement. 



REMORA, in Natural Hijlory, the fucking-fjh ; a little 

 fifh, refembling a herring, called by the Greeks echeneis, 

 famous for flicking to the fides of fhips. It belongs to 

 the genus of echeneis and clafs of thoracici in the Linnxan 

 fyftem. 



Its characters, according to Artedi and Linnaeus, are 

 thefe : the branchioftege membrane on each fide contains 

 about ten bones ; the head is thick, depreffed, naked, and 

 marked on the upper fide with tranfverfe rough flriae ; the 

 body is oblong, roundifh, and naked, but fomewhat com- 

 preffed ; the back-fin is oblong, and placed very far toward 

 the tail ; its under jaw is longer than its upper ; it has a 

 great number of teeth in both jaws ; the colour of its body 

 is hoary, and it has feven fins ; two peftoral ones, two ven- 

 tral ones placed farther from the fnout than the peftoral 

 ones, one at the anus, one on the back, and one at the tail ; 

 the flriae of the head are from eighteen to twenty-four in 

 number, they are rough and tranfverfe, but are divided as it 

 were into two feries by a middle longitudinal line. By- 

 means of thefe ftrix or ridges the fi(h can fix itfelf to any 



animal 



