Picket Machine far charging an Eleflrical Jar, §■ 



Ac board, fig. i, with its point in the fame dire<5Kon to which the fur of its cufhion inclines, 

 in order to fhew the proper application which is alfo fecured by the pins. The ends of a 

 filk ribband, two inches broad, and a yard or' 32 inches long, are neatly fcwed together with 

 filk, and the ribband afterwards fteeped in weak feed-kc varnifli. Inclofe the ribband betwixt 

 the cu(hioi>s, the arrow pointing towards the wire of the jar. The machine being expend 

 to the moderate warmth of a fire for ten or twelve minutes, efpecially in damp weather^ 

 and the cufliions made to prefs gently againft the ribband, fet the balls a quarter of an 

 inch from each other, then hold the inftrument by the boards in the left hand^ and with 

 the right hand, at a pretty good diftance from the wire in the phial, draw the ribband 

 gently, keeping the filk under the wire of the jar, and incontaft with it. At fix revolutions 

 of the ribband, the phial will generally difcharge itfelf at the above-mentioned diftance of the 

 balls. Twelve revolutions of the ribband, when the excitation is powerful, and the balls fe- 

 parated at a confiderable diftance, will produce a charge of the jar,, which few perfons would 

 choofe to receive a fecond time. Mole-(kin, with the hair on, excites filk, or the refinous plate 

 of an eledlrophorus, better than the fur of any indigenous animal the writer of this has tried: 

 this he difcovered by accident. The machine may be carried conveniently in the pocket ia 

 an oval cafe made of pafteboard. 



This inftrument is not to be eonfidered folely as a philofophical plaything ; it may be ufed 

 when a common ele<Strical machine is not at hand, as an auxiliary in recovering perfons appa- 

 rently dead by drov/ning, and other kinds of fufFocation; and when the unfortunate objects 

 are at fome diftance, it will be found not a little convenient, on account of its portable fize. 

 It may likewife be very advantageouAy applied in fome cafes of menftrual obftrudion, and iu 

 feveral morbid affeiflions where fmall fliocks are indicated. In fulpended animation froip fub- 

 merfion, (hocks of a proper degree of ftrength may be given conveniently by this inftrument 

 in the following manner, paffing each charge through the breaft, at the moment the lungs are 

 expanded by an affiftant. Apply the knob of the charged phial, held by its coating in one 

 hand to the region of the heart of the patient, at the fame time that a finger of the other hand 

 is in contail with the fpine. To avoid the fhock which the operator receives in this cafe, 

 the eledlrical circuit may be completed by means of a portable condu<3;or formed of a gold, 

 filver, or copper thread, neatly inclofed in a filk ribband, except its ends. When the phial 

 is about to be difcharged, perhaps it may be right not to fufFer any part of the patient's body 

 to come in contadl with this conduiSlor, but the ipine; and this may be effedled by means of arv 

 aiCftant, and one hand of the operator. 



III. 



On the Corundum-Jione from JJla. By the Right Honourable CHARLES Gll£rXL£,£, F.R.S, 



(Conciuded from page 544, vol. II.) 



w. 



E frequently fee fmall rhombs traced on the furface of the planes, on the ends of the- 

 hexaedral prifm, fig. 10, PI. XXIV, vol. II. This, no doubt, is occafioned alfo by the inter- 

 fedion of the laniinas, on the planes of the primitive rhomboidal parallelepiped. But thefc 



rhombs, 



