An extract of the minutes of the Royal Society, of February 19, 1746.

  • Royal Society (Great Britain)
Date:
1746]
Catalogue details

Licence: Public Domain Mark

Credit: An extract of the minutes of the Royal Society, of February 19, 1746. Source: Wellcome Collection.

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    End of the other, and then the Southern End of the firft in like Manner to the SouthernEnd of the other; from which Pofitions, being drawn afunder, it was found, that the temper’d Needle had in a Manner loft all its Virtue, but that the other would hill, with either of . its Ends, lift better than half of the Weight it lifted before. NOTE II. <c The Intention of this Experiment was to {hew how much more durable the Magnetic c Virtue was,when communicated to a Needle <c quite hard, than when given to a Needle ‘c temper’d of a Spring Temper (as it muft be €£ when touched upon a natural Loadftone) for <c by this rough Treatment the temper’dNeedle €c was render’d quite ufelefs,whereas the hard- cc en’d one was yet a Wronger than they could cc make at Deptford That Dr.Knight then touched upon the large Bars one of his fmall common magnetic Bars, in the fame Manner as he had juft before touch’d the large Needles; and this Bar,which was ap¬ plied in a contrary Direction of the Polarity it already had, had its Poles thereby inverted, and lifted after theTouch,with one of its Ends, bet¬ ter than 6 Ounces and 8 Penny-weights. That Dr. Knight laftly produced one of his large artificial armed Magnets,compofed of thin Plates of Steel cramp’d together,with which he lifted before them 31 Pounds and (jOunces.That with this Magnet, by touching in the common Way the temper’d Needle upon its armed Poles,