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j B O O K “ feflor o f mathematicks and natural philofophy in the uni“
. “ verfity of Upfala. We find him, fo early ,as the year
“ year 17 5 6 , in the:17th volume o f the Stockholm Adts,
“ corredting a miftake o f the celebrated Linnaeus 5 who, for
“ want.of more perfedt information, had defcribed, under the
“ name of coccus aquaticus, the egg o f a fpecies o f the leech
“ genus; and, in the fubfequent year, he gave an accurate
“ defcription o f that genus, which was afterwards generally
■“ adopted by Linnaeus himfelf,
•“ In 1759. he publifhpd a paper containing £ A Review
“ o f the feveral Explanations which Natural Philofophers
“ -have given -of the Rainbow f and, in 1760, fome thoughts
“ «on the Origin o f thofe kinds.of Meteors which are not
accompanied by any fenfible found or explofion and .a
“ paper on the opinions held by philofophers, relating to the
« twilight; to which he has prefixed the account o f Mairanls
« anticrjepufculum, or that of the horizon oppofite to the fun.
“ In 176 1 and 176 2 profeflor Bergman wrote, in the
“ Swediih Adts, on the fubjedt o f eledtricity, in confeqnence
“ o f a correfpondence with Mr. Wilfon^ and particularly on
“ the eledtrical quahty o f Iceland chryftal, and double re-
■“ fradting fpar. In the year 1763 he again diftinguiihed
“ himfelf among the entomologifis, by a paper on the ten-
m thredo, or faw-fly, the caterpillars of which had commonly
been confounded with thofe o f the butter-fly and moth,
“ until hedifcovered that the feet in the latter are never more
“ than fixteen, but that in the tenthredo they always exceed
“ that number. The fame year produced from the author,
“ a refult o f fome eledtrical experiments, made with filk of
“ various colours, but which did not prove fatisfadtory,
“ In 176 7 , on the reiignation o f Wallerius, Mr. Bergman
M was chofento fucceed him as pro feflor o f chymiilry ,and
metallurgy.
“ metallurgy. How ably he has filled this chair, fo honour- CHAI>-
“ ably occupied by his venerable predeceflor, is well known r . ' •
“ to all who are interefted in thefe purfuits.
“ In the year 176 4 the profeflor wrote a paper to afcer-
1 tain, from a number o f obfervations, the height in the at-
1 mofphere, at which the aurora borealis exifts. He com-
“ putes, that thefe appearances ' are fometimes fo low as at
“ 20 Swediih miles*; at others, that they are raifed to 15 o ;
“ the medium he therefore fixes at 7 2. Thefe obfervations
“ were afterwards further profecuted.
“ In 176 5 and 176 6 he wrote again on.eledtrical fubjedts,
“ and chiefly on the property and laws o f eledtricity in the
“ Tourmalin; which had been put into his. hands, by the
“ Royal Academy o f Sciences o f Stockholm, for examination.
“ In 176 7 the profeflor publiihed fome important hints
“ relative to the depuration o f alum, at the alum-works;
“ obferving, that it was cuftomary to employ alkali, in order
“ to free it from the vitriol. He advifes rather to ufe for. that
“ purpofe the admixture o f a portion o f argillaceous earth,
“ and propofes a tobacco-pipe clay.
“ A paper having appeared in the Stockholm Adis, for
“ 17 69, on the culture of pine-trees, Mr. Bergman alfo publilhed
in the fame, ‘ An account o f the Infedts which de-'
“ ftroy that Tree in Sweden and he attributes the devafta-
“ tion to the abundance o f the tenthredo caterpillar. In that
“ kingdom, where fuch immenfe quantities o f wood are con-
“ fumed in the fmelting furnaces, thefe matters are deferving
“ of high attention.
“ In 17 70, in order to induce the Swediih chymifts to
“ prepare corrofive fublimate, which was then chiefly im-
“ ported, our author publiihed a paper, containing a recital
* A degree con ta in in g iq | Swediih m ile s ; a ’Swedifli mile about Erigliili m iles,
V o l: 11^ N n n “ o f