Newton’s Principia, a work of great Im¬ 
portance, 622 ; his plan for a thermo¬ 
meter, 728, 730; for meafuring great 
heats, 733. 
Nicholfon’s hydrometer, 708, 
Noble’s pump, 756. 
Nuria, the ancient Fgvptian pump, 742, 
Ofcillation and percuffion, problems re¬ 
lating to, 621. 
Parallelogram of forces, 622. 
Panorganon, a machine for praftically 
illuftrating all the mechanical powers, 
698. 
Parent’s principle of maximum and mini¬ 
mum in machines, 621 ; in the faiU of 
wind-mills. 
Perfian wheel, 761, 2. 
Pile-engines, 695, Bunce’s, 6965 Valoue’s, 
667, 696 ; machine lor fawing off the 
heads of piles, 697; for drawing out 
piles, 698. 
Pivots or gudgeons, 670; watered or oiled, 
671. 
Pneumatics, theory of, 722. 
Projeftiles, motion of, 651; random of, 652. 
Prony’s condenfer of forces, 692. 
Pulley, and fyftem of pulleys, 631, 635, 
6 ; live and dead pulley, 672, 3 ; fkcle- 
ton pulley, 700. 
Pumps, theory of, 741-746; air-pump, 
741 ; Ctefibius’s, 742 ; fucking-pump, 
742, 3 ; converted into a lifting-pump, 
747; other modifications of, 749; 
lifting and forcing pump,' 743 ; its ef¬ 
fect doubted, 748 ; another form of, 
748; centrifugal pump, 745} Heffian, 
746; pumps without friftion, 749-51; 
quickfilver pump, 750; Todd’s, 7515 
balance-pump, 75 r, 2 ; double and triple 
pumps,752 ; for draining mines, 752-34; 
chain-pumps for fhips, 755; hand-pumps 
for fhips, 756 ; propofed method of work¬ 
ing. 758 - 
Pyrometers, for meafuring great degrees 
of heat, 733; Newton’s and Mufchen- 
broek’s, 733 ; Smeaton’s, 734; De Luc’s 
and Wedgwood’s, 736. 
Reaping-machines, 690. 
Reaumur’s fpirit-thermometer, 728 ; his 
mercurial thermometer, 731. 
Robinl'on’s method of calculating heights 
by the barometer, 726. 
Roemer, the Danifh aftronomer, 621, 2. 
Ropes, rigidity of, 675. 
Sails of windmills, 685 ; Sutton’s method 
of conftrufting, 686 ; Smeaton’s experi¬ 
ments, 686 j his machine, 693. 
Salmon’s hay-making machine, 0S9. 
Savery’s fteam-engine, 769, 770. 
Screw, 632, 3, 636; its extenfive ufe, 
633 ’ 4 > 700. 
•Segner’s theory of rotatory motion, 623-4. 
•Siphon, its principle explained, 746 ; far¬ 
ther exemplified, 747. 
MECHANICS. 
Six’s thermometer, 732. 
Smoke-jack, 694; Englifh, 695. 
Smeaton’s contrivance for making wheels 
aft in contrary direftions, 672; for 
windmill-fails, 686, 693 ; his opiniou 
of horizontal windmills, 687 ; his py¬ 
rometer, 734; hand-pump for fhips, 
756 ; water-mill, 768. 
Smith’s reaping-machine, 690-692. 
Snart’s horfe-helper, 682 j aerometer, 
709 ; chondrometer, 710. 
Snodgrafs’s method of heating rcoma with 
fleam, 793. 
Sound, phenomena of, 739. 
Space, abfolute and relative, 624. 
Specific gravity, 701 ; defined and explain¬ 
ed, 704; inftrumenls for meafuring, 
706-710. 
Springs recommended forearts, 680, 683, 
Springs of water, phenomena of, 740, 747. 
Stage-coach upon an improved principle, 
681,682. 
Steam-engines, 769-796; general princi¬ 
ples, 769 ; Savery’s, 769, 770 ; New¬ 
comen’s, 769-772 ; improved by Beiglr- 
tdn, 775; Woolf’s application of a 
rotatory motion to, 776; Watt’s firft 
fleam-engine, 777; fecond, 778 ; laft 
improvement, 780 ; Hornblower’s, 783 ; 
Woolf’s, 784,5; for impelling boats, 
786 ; and fhips, 787 ; for drawing car¬ 
riages, 790 ; for cooking, 791; warming 
rooms, 793 ; for fupplying hot-houfei, 
794- 
Steelyard, 631. 
Stevinus, a Dutch mathematician, 620. 
Strap-work, 669, 70, 2. 
Strength and ftrefs of materials, 653 ; 
theory of Galileo, 653 ; confirmed by Du- 
hamel’s experiments, 654; thefe ex¬ 
periments have been chiefly confined to 
wood, not to be reduced to mathematical 
calculation, 654; experiments of Muf- 
chenbroek and Emerfon, chiefly on wood. 
657; experiments on metals, 658; 
Banks’s experiments on call: iron, 659 5 
machine for making experiments, 693. 
Tantalus’s cup, 746. 
Taylor’s hand-pumps for fhips, 757. 
Technical terms, remarks on, 618. 
Teeth of wheels, 661 5 Dr. Robinfon’s 
fcheme, 663, 4. 
Thermometers, various kinds, 727-737 ; 
air, and fpirit, 727 ; oil, and mercury, 
728; conftruftion of, 729; Fahrenheit’s 
730; Delifle’s, Reaumur’s, &c. 731; 
felf regiftering, 731, 2; differential, 
733; for meafuring great degrees of 
heat, 733. See Pyrometer. 
Thrafhing-machines, hiftory of, 688 j a 
fmall one to work by hand, 689. 
Time, relative and abfolute, 625. 
Todd’s improvement of the pump, 751. 
Torricelli, a follower of Galileo, 620. 
Valoue’s pile-engine, 667, 696 ; its theory 
fully explained, 697. 
Valerius,called the modern Archimedes,620. 
Vapours, how formed, 739, 40. 
Varignon’s lever impoflible, 617 j his ap¬ 
plication of ftatics to the equilibrium of 
machines, 621. 
Velocity, or celerity, 625. 
Vera’s hair-rope machine, 755. 
Vince’s experiments on friftion, 673 ; on 
fpouting fluids, 718 ; on the velocity of 
found, 739. 
’Vis inertia, or gravity, 625. 
'Wakefield’s fteam-houfe for plants, fruits, 
and flowers, 794. 
Water-mills overfhot, 762, 766; breaft, 
762, 765 ; underfhut, 763, 767 ; with 
oblique float-boards, 764; with con¬ 
cave float-boards, 765; Fergsfon’s di¬ 
reftions for the conftruftion of water¬ 
mills, 766; floating, 768. 
Watt’3 fteam-engine, general principle of, 
770; his firft attempts, 777 ; his fecond 
engine, 778 5 his laft improved engine, 
780. 
Wedge, 634, 636, 700. 
Wedgwood’s pyrometer, 736; Fourmy’s 
objeftions, 736. 
Weight diftinguifhed from gravity, 641. 
Wheel and axle, 631, 635 ; with contrary 
motions, 672. 
Wheels, teeth of, 661; aftion of wheels 
and pinions, 662; bevelled wheels, 664; 
rack-work and wipers, 665; fly-wheels, 
666 ; carriage-wheels,'675 ; proper fhape 
of, 676 ; other properties, 677 ; Edg- 
worth’s experiments, 679 ; overfhot 
and breaft wheels for mills, 762 ; un- 
derfhot wheels, 763 ; with oblique float- 
boards, 764; with concave float-boards, 
765; advantages of the different kinds, 
766. 
Wheel-carriages, 677; Edgworth’s experi¬ 
ments, 679 ; improved ftage-coach, 681, 
2 ; Braby’s cart and drag, 682, 3 ; fprings 
recommended for all carriages, 683 ; 
placing fome of the horfes behind,J)83, 4* 
Winds, phenomena of, 737; periodical, 
accounted for, 738. 
Wind-mills, aftion and early hiftory of, 
684; common wind-mill, and its fails, 
685 ; horizontal wind-mills, 687. 
Wood, ftrength of, 656. 
Woolf, Arthur, his contrivance for com¬ 
municating a rotatory motion to fteam- 
engines, 776 ; his patent fteam-engines 
for faving fuel, &c. 784, 5. 
Wren, his demonftration of the laws of 
percuffion, 621. 
Young, Dr. Matthew, his experiments on 
fpouting fluids, 718 ; his opinions on ca¬ 
pillary attraftion, 720. 
Zurich machine, a kind of pump, 758; 
ditnenfions of one made at Florence, 760. 
