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The Philosophical transactions of the Royal society of London, from their commencement in 1665, in the year 1800 (Volume 8) online

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Inflammable Air, John Maud 77

On Barometers, H. Beigliton 198

Foul Air in a Well, B. Cooke 244

Force of Steam, J. Clay tonr 335

I' age

Force of Steam, J. Payne 518

Sutton's Ventilators, Dr. Mead 553

, Wm. Watson 56o

Heights of Barometers, 8. C. HoUman . . 578

8. Optics.

Combinations of Lenses, J . Hadley 54

Catoptric Microscope, Dr. Barker 73

Catoptric Telescopes, C. Smith 393

Leuwenhoeck's Microscopes, H. Baker . . . 44S

Grinding of Lenses, Sam. Jenkins 451

A Reflecting Instrument, Sir L Newton . . 590

g. Magnetism, Electricity, Thermometry.

The Electrical Light, Stephen Gray 2

Magnetism by Lightning, Dr. Cookson . . 24,25
Electrical Experiments, Stephen Gray .... 51
Electrical Rotation in Bodies, Stejjhen Gray 65

Quicksilver Thermometer, De Lisle 66'

Magnetical Variations, Middleton 76

Expansion of Metals by Heat, Ellicott ... 82
Magnet. Needle aft'ectcd by Cold, Middleton 224
Magnets of more than 2 Poles, J. Eames . . 246
Magnetical Experiments, Desaguliers. . 246,247
, Gr. Wheeler ... 306

On the same Experiments, Dr. Mortimer. . 313
On Gray's Electrical Rotations, Wheeler.. 3l6
Variation of the Compass, W. Hoxton . . . 339

Cause of Electricity, Desaguliers 340

Electrical Experiments, Desaguliers 346,350,351,
352,353,357 ,470,472,473,479
Magnetism by Lightning, De Bremond . . . 483
Observations on Electricity, Desaguliers . . 546
Uncommon Warmth of Air, H. Miles . . . 548
Electrical Conjectures, Desaguliers 584

Class III. Natural History.

1. Zoology.

Catesby's Natural History of Carolina, Mor- Phoca, or Sea Calf, Dr. Parsons 658

timer 32,73,235 Eels in Vinegar, H. Miles 674,

Moose-Deer, Stag, Flying Squirrel, Dale 102 Fresh -wrater Polypus, Mart. Folkes 67S

Narhwal, or Unicom Fish, Steigertahl. . . . ]60 Observations on Insects, Bonnet 6821

— , Dr. J. H. Hampe . . 16I On Polypi, by the Duke of Richmond .... 685

Uncommon Water Insect, Klein ibid Worms living after cut, Thomas Lord .... 692

, by Brown and Mortimer l63 A Zoophyton, G. Hughes 717

Worms that destroy Timber, Dr. Raster . . 378 A Dried Polype, H. Baker 724

Sun-Fish, and its Glue, Wm. Barlow 402 Worms in Smutty Com, T. Needham 7J9

Teeth of the Rattle Snake, Dr. Bartram . . 409

2. Botany.

Catalogue of 50 Plants, Isaac Rand 1,54,113,


Botanical Observations, Moekring 358

Letters within a Tree, Klein 359

Deer's Horn in an Oak, Sir J. Clark 360

Remarks on the same. Dr. Mortimer . .
Scurvey-grass of Greenland, Nicholson
Haller's Enum. Math. Slirp., Watson . .
Catalogue of 50 Plants, Jos. Miller . . . .

3. Mineralogy.

Copper-water in Mines, Mat. Bell 236

Spirit of Coals, John Clayton 295

Nitrous Particles in the Air, Clayton .... 296

Petrifactions at Matlock, Mort. Gilks 406

Le Bruyn's Petrified Oysters, Klein 455

Coal-balls at Liege, &c. Hamburgh . .
Observ. at Hudson's Bay, Middleton
Nature of Amber, J. A. Beurer . , , .
Malmy Concretions, T. Needhara . . .







4. Geography and Topography.


Figure of the Earth, J. Stirling 26

Spherical Maps, John Colson 6l

Figure of the Earth, Clairaut 118

Measure of the Earth in Russia, De Lisle. . 124

Measure of a Base for the same, ditto .... 134

Cavern at Pyrmont, J. P. Seip 204

Bell's Hist, of Hungary, Dr. Pearce 253

Two Curious Caverns, Mat. Bell . .' 293

Manners in Virginia, J. Clayton 328

Eruption of Vesuvius, Aragona 36l

The same, by an English Gentleman ...... 368

Sinking of Ground, P. H. ZoUman 376

New Terrestrial Globes, Mr. Harris 393


Aretina near Naples, Wm. Sloane 403

Kilcorny Cave, C. Lucas 4.09

Celsius's Figure of thfe Earth, Fames .... 413
Degree of Lat. near New York, Alexander 419

Herculaneum at Portici, C. Paderni 435

, Geo. Knapton . . . 437

, Mr. Crispe 438

Observ. in the Tyrol Alps, Ehrhart 4.J1

Lake Malholm Tarn, J. Fuller 463

Dead Sea Waters, Dr. Charles Parry 535

Account of Bridgnorth, Stackhouse 581

Of Hudson's Bay, Capt. Middleton 591

Of Greenland, Dr. J. Green 722

Mexican Filtering Stone, Dr. Vater 30

High Tide in the Thames, Tho. Jones .... 59


Diving Bell, Mart. Triewald


Class IV. Chemical Philosophy.


Seignette's and other Salts, Geoflfroy 10

Experiments on Quicksilver, Boerhaave. . 93j98

Experiments on Ice, Abbe NoUet 223

Oil of Sassafras Crystallized, J. Maud .... 243


West-Ashton Waters, G. Haukewitz .... 522

Cheltenham Waters. Senckenberg 523

Dulwich Waters, J. Marty n ibi<

Frobenius's Spir. Vini ./Eth. Mortimer .... 53i

2. Meteorology.

Earthquakes in New England, P. Dudley 22

Halo observed at Rome, Revillas 32

Zigzag Figure of Lightning, Ja. Logan ... 68

Aurora Borealis, Andrew Celsius 69

Of a Great Storm, Henry Forth 78

Earthquake in Sussex, D. of Richmond ... ^6

On the same. Dr. Edward Bayley ibid

Earthquake in Northampton, J. Wasse. ... 98

Parhelia and Aurora Borealis, T. Neve ... 134

Two Parhelia, Weidler 136

Three Mock-Suns, Martin Folkes 137

Meteorological Diaries, J. Hadley l63

Meteorological Observations, Poleni 196

Sulphur gener. in the Air, B. Cooke 264

An Anthelim, Weidler 358

Whirlwind at Come Abbas, J. Dorby 35?

Effects of Thunder on Trees, Sir J. Clark 360

Explosions in the Air, A. Vievar 383

On the same, Sam. Shepheard 384

Earthquake at Naples, H. Temple 401

Meteor in the Air, M. Crocker 403

Luminous Appearance, Dr. Bevis 404

Meteors at Philadelphia, Breintnall 409

Aurora Borealis, James Short 412

On Weidler's Parhelia 433

Dry or Wet Summer, Anonymous 447

Red Lights seen in the Air 457

Several Meteors, Thomas Short 469

Weather, &c. George Lynn 486

Aurora Borealis at Rome, Revillas 502

Earthquake at Scarborough, Johnson 514

Aurora Borealis, Dr. Mortimer 525

, J. Martyn ibid

, Tim. Neave 526

Hurricane in Huntingdonshire, Fuller .... 530

Fire-ball Explosion, Lord Beauchamp .... 540

, J. Fuller ibid

, William Gostling .... 541

, Charles Mason ibid

, Benjamin Cooke 550

Earthquakes in America, M. Plant 552

On Parhelia, H. Miles 555

On a Fire-ball, Capt. Wm. Gordon 559

, Wm. Gostling 56O

Earthquakes at I-eghorn 568

Dew and Snow-flakes, Dr. L. Stocke .... 577

Effects of Lightning, Lord Petrie 583

A Meteor, Dr. Thomas Milner 583

Meteor in Norfolk, Lord Lovell 604

Meteorological Register, Revillas 606

Meteorological Observations, G. Hadley . . 6l7



Class V. Physiology.

I . Anatomy.


Foramen Ovale open, C. Amyand 54

Bones of Mammoth or Elephant, Bryne .. 155

Gigantic Bregma, &c. Klem 388

Monstrous Child, T. Sheldrake 401

Stuart's Structure of the Heart, Mortinaer 483

Foramen Ovale and Ureflira, Le Cat 485

Monstrous Foetus, Wm. Gregory 503


Heart upside down, De Torres 508

De Sceletorum, &c. S. C. HoUman 513

Polypi in the Heart, Dr Huxham 580

Sfieaking without a Tongue, H. Baker .... 586

Articulating Cartilages, Wm. Hunter .... 686

Monstrous Large Child, Geoffroy 727

2. Physiology of Animals.

Bones coloured Red by Food, J. Belchier 79,83

A Monstrous Boy, Dr. Cantwell 325

A Girl a Quarter of an Hour in Water with-
out Drowning, J. Green 337

Generation and Monsters, Super\'ille 385

Bones tinged by Madder Root, Du Hamel 420
Dr. Trew on the Difference between the

Body before and after Birth, Da. Hartley 425
A Beetle lived 3 Years without Food, Baker 426

On Hermaphrodites, Dr. Parsons 477

Circulation of Blood in Efts, H. Miles 501

Extraordinary Skeleton, and a Man who gave

Suck, Bishop of Cork 5i6

Remarkable Birtli, C. Warwick 589

On a Polypus, J. F. Gronovius 607

, a Cambridge Gentleman . . 609

A Man who lived 18 Years on Water,

R. Campbell 616

Experiments on the Polypus, M. Trembley 623
Stat. Experiments on himself. Dr. Lining 683
Worms living after cut, Thomas Lord .... 692
Cells of Honeycomb, Maclaurin 709

3. Physiology of Plants.

Impregnation of Plant Seeds, Ja. Logan . . 57

Oil of Sassafras Crystallized, J. Maud 243

The Smut in Corn, Abbe Pluche 408

A Plant in Semine, H. Baker 429

Seeds of Fern, H, Miles 505

Veget. of Old Melon Seeds, Triewald 577

Great Increase of Seeds, Hobson 63 1

Seeds of Mushrooms, R. Pickering 718

Remarks on the same, Wm. Watson .... 721

Farina of Red Lilly, T. Needham 729

4. Medicine.

On a Cataleptic Patient, Rd. Reyuell .... 15

Experiments on Mad Dogs, Dr. James ... 69

Bones Coloured by Food, J. Belchier 79

Remedy for Vipers bite. Dr. Burton 84

On ditto, and Mad Dogs, Mortimer 84

Bite of Vipers, Dr. Atwell 107

Cure of t)ie same, Ste. Williams 124

Peruvian or Jesuits Bark, John Gray 142

Dampier's Powder for Canine Madness, J.

Fuller 204

Bite of Mad Dogs, Hartley and Sandys . . 205

Biliary Ducts and Gall-bladder, Amyand . . 228

On the same case. Dr. Stuart 232

On Dr. Huxham's Book De Aere et Morbis

Epidemicis, by Dr. Stock 265

Cure for Viper? bite, Dufay 267

Poison of Henbane Roots, Patouillat .... ibid

Cure for Canine Madness, T. Steward .... 269

Poison of Laurel Water, Dr. Rutty 297

Limgs coughed up, Wm. Watson 46'8


Black currant Jelly, H. Baker 479

Extraordinary Venereal Case, Huxham. . . . 480
Hairy Substances voided by Urine, Powell 489

On the same, by Sir Hans Sloane 49O

On the same, by T. Knight 491

Watery Cystises, Dr. Graham 492

Hydatids per Vaginam, Wm. Watson .... 494

On the same by Le Cat 495

On Orme's Pectoral Syrup 505

Antidote tothe Westlndian Poison, Milward 542

Stones in the Bladder, E. Nourse 545

On the same Subject, George Bell 557

Extraordinary Dropsy, Gronovius 607

A Man living 18 Years on Water, Campbell 616

Two Medical Cases, Dr. Raster 622

Calculus voided by Urine, Leprotti 653

Grandgor, the Venereal Disease, Maclaurin 675

Bones becoming Soft, S. Bevan 682

Bloody Urine in the Small- Pox, Dr. Dodd 708


Fistula Ljicrymalis, Hunauld

Bony Substance in the Womb, Dr. Hody. .

Perforations in the Thorax, Hauston

Plum-stone in the Rectum, Madden

Inguinal Rupture, &c. Amyand

Rupture of the Ilium, Chr. Wolf.

Tumour in the Pelvis, Dr. Cantwell

Palsy of the Eyelids, by the same

Arm torn oft' by a Mill, Belchier

Bullet lodged near the Gullet, Ld. Carpenter
Biliary Ducts and Gall-bladder, Amyand . .

On the same Case, Dr. Alex. Stuart

On a Bubonocele, C. Amyand

Pin in a Child's Bladder, W. Gregory ....
Calculus in the Bladder, De Caumont ....

On the same Case, Salien

On the same, by Sir Hans Sloane

Part of the Spleen lost, J. Ferguson

Tumour in the Knee, Jer. Peirce

Wound in the Cornea of the Eye, T. Baker

Three Cases in Surgery, Sherman

Pestilential Fever by Tapping a Corpse dead

of a Dropsy, Cox

Calculus through the Perin. Hartley

Calculus through the Scrotum, Sisley ....

Tumour on the Thigh, Malfalguerat

Exostosis on a Boy's back, Freeke

. Surgery.

Page Page

17 Wound in the Head cured, Cagua 439

56 Stone voided per Anum, Mackarness 441

68 Calculi in the Stomach, Dr. Breyne 452

80 Machine to reduce Fractures, Ettrick .... 454

89 Stones in the Kidneys, N. Sherwood 462

138 Softening of the Bones, P. Pott 464

158 Hernia Inguinalis, Dr. Huxham 474

225 Foetus 9 years in the Womb, Bromfield . . 489

226' Hair}' Substance voided by Urine, Powell. . ibid

227 Singular Hernia, Le Cat 497

228 Fracture of the Thigh, Wm. Wright 503

232 Needle through the Arm and Breast 504

236 Caesarian Operation by a Butcher 517

239 Catheter for the Stone, A. Cleland 526

240 Instrument for the Eye and Ear, Cleland . . 528

241 Steelyard Swing, T. Sheldrake 549

242 Klein's History of Fishes, Eanies 551

263 Preserving Fish Skins, Gronovius 559

'i9i Internal Cancers, Dr. Burton 572

324 Le Cat's Treatise on the Senses, Dr. Parsons 619

326 Medico-Chirurg. Observ. Schlichting 620

Hammock for dressing Patients, Le Cat . . 654

338 Ambe of Hippocrates, Le Cat 659

405 Instrument to reduce dislocated Shoulders,

ibid Freke 706

410 Extraordinary Haemorrhage, Dr. Banyer . . 727

413 Ascites cured by Tapping, Banyer ibid

Class VI. The Arts.
1. Mechanical.

Standard Measures at Rome, Folkes 7*

New Water Bellows, Triewald 192

Weights and Measures, Wm. Barlow .... 432

Grinding Lenses, Sam. Jenkins 451

English and French Wts. and Mea. Comm. 604
Standard Weights and Measures, Committee 698

2. Chemical.
On Soap-making, GeofFroy 565

, - 3. Fine.

Gold-coloured Glazing, Heinsius 606

4. Antiquities,

On an Ancient Date, John Cope

On the same, John Ward

On the same again, J. Cope

Again on the same, J. Ward

Ancient Chirograph, R. Gale

Runic Characters, Celsius

Roman Stamps like printing, Mortimer

Antiquities of Pnissia, Klein

Weights and Measures, Barlow

Barrows in Cornwall, Williams

32 Herculaneum at Portici, Pademi ........ 435

ibid On the same, by Geo. Knapton 437

37 On the same again, Crispe 438

39 Roman Pigs of Lead, Kirkshaw 453

64 Ancient Date at Rumsey, Barlow 478

1 14 Roman Hypocaustum, Sympson 532

248 A Golden Torques, Sir Tho. Mostyn 550

420 Standard Weights and Measures, Committee 698

432 Ancient Temple, and Stone Hatchet, Bp. of

433 Cork 715



Class VII. Bibliography ; or, Account of Books.


Newton's Fluxions by Colson, Eames 88

Muller's Conic Sections, J. Earaes 145

Bell's History of Hungary, Z. Pearce 253

Huxham, De Acre et Morb. Epid. Stack. . 265
Fourmont'sHistoriesof the Ancients, Pearce 389
Celsius on the Figure of the Earth, Eames 413
Dr. Trew on the Difference of the Body

before and after Birth, Da. Hartley 425

Le Bruyn on Petrified Ousters, Klein 455


Dr. Stuart on the Struc. of the Heart, Mort. 483

Klein's History of Fishes, Eames 551

Kersseboom on the Number of Persons in

Holland, Van Rixtel 628

Maclaurin's Fluxions, Maclaurin .... 632, 667
Haller's Enumeratio Methodica Stirpium

Helvetiae, &c. Watson 655

Robins' Principles of Gunnery, Robins. . . . 677

Class VIII. Biography ; or. Account of Authors.



Bevis, Dr. J

, 117

Du Hamel


Baster, Dr. Job.

. 378

Ehrhart, B


Baker, Henry . .

, 426



Bruyn, C

. 455

Hartley, Da




Haller, Alb




Hunter, Dr. Wm.


James, Dr. R. , , . 69

Le Cat 485

Muller, J 145

NoUet 223

Pearce, Zac 389

Pluche, Ab 408

Pot, Percival . , . 464

Parsons, Dr 692

Seignette 10

Senex, John .... 176

Stone, Edm 392


Plate I, Fig. I, II, III, 6; IV, V, 7; VI, 8j VII, VIII, IX, 9; X, 10.

II, . . 1, II, 12} III, 13; IV, 32; V, 26j VI, VII, 56; VIII, 100.
ni, . . I to V, 44; VI, VII, 45; VIII, IX, 46; X, XI, 47; XII, XIII, 48; XIV, 49;.

XV, XVI, 50.
IV, ..I to V, 74; VI, 82; VII, 103; VIII, 104; IX, X, 105; XI, 106; XII, 120;
XIII, 121 ; XIV, 122.
V, . . I to X[V, 114; XV, 136; XVI, 138.
VI, .. I, l6l; II to V. 162; VI, 163; VII, 183; VIII, 192; IX, 208; X, 209;
XI, XII, 210; XIII, 212; XIV, 213; XV, 217.
VII, . . I, 241; II, 249; III, 260 and 262; IV, V, 284; VI, 286; VII, VIII, 342ir

IX, X, 343; XI to XIV, 344; XV to XVIII, 345.
VIII, .. I, 353; II, 357; III, 371; IV, 372; V, 375; VI to XIII, 382.
IX, . . I, II, 393; III, 395; IV, 396; V, 400; VI, 429; VII, 434; VIII, 454; IX, 478.
X, . . I, 454; II, in, 459; IV, V, 486; VI, VII, VIII, 486; IX, 508; X, 507.
XI, . . I, 509; II, III, 510; IV, 511; V, 519; VI, 521.
XII, . . I to VII, 528; VIII to X, 529; XI to XIII, 530,

XIII, . . I, II, 532; III, IV, V, 533.

XIV, . . I, II, 535; III, 536; IV, 550; V, VI, VII, VIII, 577; IX, 590; X, 623; XI,
654; XII, 655.

XV, . . I, II, 659 ; HI, 661; IV, 659.
XVI, . . I, 661 ; II, III, 662; IV to IX, 662 and 663.
XVII, .. I to XIII, 666 and 677.
XVIII, .. I, II, III, 686; IV, 691; V, VI, VII, 698.
XIX, .. I to IX, 698,
XX, . . I, 717; II, 706.
XXI, . . I, II, 710; III, 712; IV, 718; V, VI, VII, 720; VIII, 725,






ji Catalogue of the 50 Plants, from Chelsea Garden, presented to the Royal
Society by the Company of Apothecaries, for the Year 1733, pursuant to the
JDirections of Sir Hans Sloane, Bart. By Isaac Rand, Apothecary, F. R. S.
N" 436, p. 1 . Fol. XXXIX.

JL HE 12th annual present of the 50 plants, making in all 60O.

A Catalogue of the Eclipses of Jupitei-''s Satellites, for the Year 1736, computed
to the Meridian of the Royal Observatory at Greenwich. By J. Hodgson,
F. R. S. Master of the Royal Mathematical School in Christ's Hospital.
N° 436, p. 5.

Mr. Hodgson's usual catalogue of these eclipses, precalculated, to compare
with observations when they should be made.

The Apparent Times of such of the Immersions and Emersions of Jupiter s
Satellites, as are visible at London, in the Year 1736, with their Configura-
tions at those Times. By Mr. Hodgson. N° 436, p. 13.

O the same nature, and for the same use as the former.

Account of the Observations of the Eclipses of the First Satellite of Jupiter, com-
pared with the Tables. By the same. N° 436, p. 15.

By comparing 244 eclipses of Jupiter's first satellite, observed between the
years l677 and 1731, with the Flamsteedian tables, corrected by Mr. Hodgson,
he finds there are 74 that do not differ 1 minute from the tables ; 127 that do

VOL. vm. B


not differ 1 minutes; 181 that do not differ 3 minutes ; and 214 that do not
differ 4 minutes ; the rest not differing above 5\ minutes.

Experiments and Observations on the Light, produced by communicating Electri-
cal Attraction to animate or inanimate Bodies; ivith some of its most surprising
Effects. By Mr. Stephen Gray. N° 436, p. l6.

The several new electrical discoveries made by M. Dufay, especially that im-
portant luciferous one, mentioned in a former Transaction, led Mr. Gray to
make the following experiments : —

He began first with some common utensils that were at hand, as the iron
poker, tongs and fire-shovel ; any of these being suspended on lines of the
largest sewing silk, and then the excited tube being applied first to the knob of
the poker, and afterwards to the hand, the snap and pricking were felt ; and
the effect was the same, when the tube was first applied to the other end of the
poker. He had by him a three-pronged iron instrument, made many years be-
fore ; being designed for propping up the observatory table, when he observed
the spots in the sun. The prongs were about 4- an inch in diameter, two of
them about 22 inches, and the third about 8 inches long, and pointed. This
being laid either on cylinders of glass, or cakes of rosin and bees-wax, or on a
cake of sulphur, the tube being applied to the end of any of the legs, while
the hand or cheek was applied near the other, both the other legs had the same
effect, as that to which the tube had been applied ; but by holding his cheek
near any of the points of the legs, the pricking or burning pain was much
more sensibly felt, and even sometimes for several minutes after.

As to the success in repeating M. Dufay's experiment at Mr. Wiieeler's,
they procured silk lines strong enough to bear the weight of his foot-boy, a
good stout lad : then having suspended him on the lines, the tube being applied
to his feet or hands, and the finger of any one that stood by held near his
hands or face, he found himself pricked or burnt, as it were, by a spark of fire,
and the snapping noise was heard at the same time: but it did not succeed when
they applied their hands to any part of his body through his clothes, except
upon his legs, where he felt the pain through his stockings, though they were
very thick ones.

They took also a large white cock, and suspending him on the lines, first
alive, the effect was the same as on the boy, whether they applied their fingers
to any part of his body, or their cheek to his beak, or comb or claws. The
cock was then killed, and put on the lines again ; when they found very little,
if any difference, from the effect it had when the cock was living. They then


caused the cock to be stripped of all his feathers ; and the difference was still
not very considerable.

They took a large surloin of beef, and suspended it on the silk-lines : then,
on holding the fingers near any part of it, there was a snapping, and the fingers
were pushed or pricked : but the snapping was thought not to be quite so loud,
as when the experiment was made on the cock.

They caused to be made an iron rod, 4 feet long, and about half an inch
diameter, blunt pointed at each end. This was suspended on the lines : then
the tube being rubbed, and held near one end of the rod ; and then the finger
or cheek being put near either end of it, the effect was the same as when
an animal was suspended on the line, with respect to the pricking pain.

At night they made the luminous part of the experiment ; suspending the
iron rod on the silk lines ; then applying one end of the tube to one end of the
rod, not only that end had a light on it ; but there proceeded a light at the same
time from the other end, in form of a cone, the vertex being at the end of the
rod ; and it plainly consisted of rays of light, diverging from the point of
the rod ; and the exterior rays incurvated. This light is attended with a small
hissing noise ; and every stroke given to the tube, causes the light to appear.
The hissing seems to begin at that end of the rod next the tube ; and as it
comes, increases in loudness ; but it is so small as not to be heard without good
attention, and by those only that stand at the end of the rod from whence the
said light proceeds.

Mr. Gray repeated the experiments, by laying a rod of iron on a cake of
shell-lac, which was laid on a glass-vessel : and the effects were much the same
as mentioned above.

Having caused to be made 3 iron rods, one 4 feet long, and two 3 feet long
each ; one of these was made tapering towards the ends, and pointed as that of
4 feet was ; the other pointed at one end, and the other end not pointed, the
diameter of the rods about half an inch ; they were first forged, then filed and
burnished. With these Mr. Gray made the following experiments : when any
of them were laid on the brims of hollow cylinders of glass well warmed, or
on cakes of rosin and bees-wax, or on those of sulphur, the phenomenon was
the same, as when they had been suspended on silk lines. But now he dis^
covered a very surprising one, viz. that after the tube had been applied, and the
light seen at both ends, on going to the other end of the rod, when there was
no light to be seen, and holding his hand at some distance from it, then moving
his hand towards it with a pretty swift motion, there issued from that point of
the rod a cone of light, as when the tube had been applied to the end : and on
repeating this motion of his hand, the same phenomenon appeared for 5 or 6

B 1


times successively, only the rays were each time shorter than the former : and
these lights were attended with a hissing noise. The light which appears on
that end next the tube, when it is held obliquely to the axis of the rod, has its
range tending towards it. All the time he is rubbing the tube, these flashes of
light appear on every motion of his hand, up or down the tube; but the largest
flashes are produced by the downward motion of the hand.

When several rods are laid either in a right line, or forming any angle with
each other ; and either touching, or are at a small distance from each other ;
the tube being applied to one of their ends, the farthest end of the farthest rod
exhibits the same phaenomena, as one single rod does.

An experiment with the rod pointed at one end only. When the tube is ap-
plied to the other end, the point exhibits the same appearance, and a like effect,
as the rods that are pointed at each end ; but the great end of the rod, when
the hand or cheek is applied near it, gives but one single snap ; though this is
much louder than the greatest of those from the pointed end, and it gives a
little more pain.

Having forged an iron ball, 2 inches diameter, and then turned and burnished
it; having placed it on a wooden stand with a small concave on the top, in
which the ball was placed: the stand being set on a cylindric glass, and the
excited tube being applied near the ball, a stream of light proceeded from it,
with a small hissing noise : but putting his finger or cheek near the ball, no

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