166 0;,~ H/aler t~heel6',

ping at intervals, but returning with redoubled force. In this Mat~ a strong current of air proceeds from the wire and its conaected ap- paratus; anti none but a spectator caI~ conceive the awful, through sublime, etf?ct, of such phenomena. At every flash of lightning, an explosive stream: accompanied by a peculiar noise~ passes between the balls of the apparatus, and e~Iighterls, most brilliantly, e~ery sur- rounding object, whilst tbese etfects are heightened by the successP~e peals of thunder, and by the consciousness of so near an approach to its cause."

"Durir~g the display of electric power~ so awful to an ordinary observer, tim electrician sits quietly in fi'ont of the apparatus~ con- ducts the lightnin,~ i~ any reriuired direction, and employs it to luse wn.es, decnmpose~iluids(or i~re inflammable substances; and ,M~eu

• t l : eiti~cts are too powerful, to attend to such experiments securely, h. com~ects the insulated wire with the ground~ and transmits the accumulated electricity ~ith sihmce, and with safety."

FO]{ THE FIlANKL1N JOUI~.N£Lo

Remarks upon littler fVhcds, .~d ~qJo~ some prevailing error,~ ~'eo specliJ~g the J]HJlication of water (~s a Motive Power.

I sucrose,: that, at the present dily, no man who professes to be capable of directing the constructiem of a water wheel, or of estimat- ing the amount of a water power, is ianorant of the thct, that water falls through it distance of aboutsixt~c~ feet in the first second. Bin. I suspect that mary who assumethe above qualifications, do not know the ratio of increase, either of the distance, or the velocity, l have drawn this conclusion, not only fl'om cot~versafions ~,itt~ se~e- ral practical engineers, but also froff~ essays published in ~ur scien- tilie journals. )ks an instance of the latter~ l will select, fi,r its c~n- venience of reference, ai~ article on water wheels published in this Journal (Vol. I[. p. {0S.) which bein~ the production of a practical' engineer, and having passed tim mspectmt~ o{ a scmntfim committee, may be considered as corroborating my commenclng observed:ms. In the third para,'raph of that article, is the followh~g sentence: As a falhng body~ water descends at the speed of nearly 16 teet Jn the first second, aml it will appear evident, that if a water wheel is re- quired to be so driven, that the water with which it is loaded has lo descertd 1G 11~ or 1~ feet per second, at which rates wheels are generally constructed to work, that a very Nr,ge prol)orlion of the power is lost."

liere,, in tl~e lirsI, place,..we lind si)eed,, or vdocit, y , confounded with the di.stance fitllen m the hrst second; wlmreas, the latter is If5 feet, and the tbrmer is accelerated, from nothing, at the cmmnenceme~t, to 3~2 feet per second~ at the end of the first second- so that this part of the

,sentence conveys, .~trictly, no intelligible meaning; it is, neverthe- less: made ;~ sta~,lar G by a comparison bt, tween which, and any

On tI'a/er T'Vheels. 167

aiven velocity of ' t water wheel, we are to infer tile loss of power ~'ustained th~'~ough excess of speed'; thus, in the case of a wheel whose velocity is 10, or 1~, feet per second, comparing these numbers with the my~terised number 16, the writer concludes, " tha t a very larRe proportion of the power is lost." The height, of the fall which indi- cates the whole amount of the power, is not mentioned, but surely, to estimate the proportion between a defined part, and an undefined whole, is impossible.

The vazue appreciation of first principles which I impute to this writer, is'~exhib'it'ed conclusively, it'~ his closing remarks on certain establishments which he had inspected. At the corn mill on the Raft- ton, as well as at the flout, mills on the Brandywine, he represents the fall of water to be,~0 feet, the diameter of the wheels ~bout 16 feet, and the speed of their skirts about 1O feet per second, worked by a head of 4 "feet; from which be draws the deplorable conclusion, that "in all these establishments there is not obtained 50 per cent. of the power of the water used." But, a little simple arithmetic will furnisl~ the proprietors of these mills with a more satisfactory account, and, perhaps, prevent their incurring the expense of a new arrange- merit, wit]; a view to realizing the lost 50 per cent. of their power.

The velocity of the skirts of the wheels is 10 feetper second; this velocity is acquired by water in a descent of 18-? inches. ~ But the water issues upon the'wheels from under a head of 4 feet, under which its effluent velocity is 16 feet per second. Now, although the wheels are not much ass{ste(l by th'e impulsive power of the Water, striking upon them with a velocity 6 thet greater than their own, yet they are certainly not retarded by it, and therefore, on no ground can we make the loss" more than 4 feet; which is but one-fifth of the whole power or flfll of £0 feet, leaving four-fifths as the proportion of the power effectively applied, instead of less than one half, as as- serted in the article under consideration.

Our water works at Fair Mount, which so justly excite the pride of our citizens, and their gratitude to those publid-spirited individu- als to whose enterprise and skill we are indebted for them, come next in review; but as his information on some important points in this case, is incorrect, I need not enter into an exi~mination of bis conclusions; I will however, venture to oft~r my own views on the subject of tile economy, and application, of the power consumed.

~i~he head and fall, at high title, is 6 feet 6 inches, the wheel, at this time, wading ~ feet in the tide; when the tide is out, it is 8 feet 6 inches, and as the tide rises and falls about 6 feet, twice in g5 hours, I suppose the wheels wade, more or less, for about 7 or 8 hours out of every 0~4; I will therefore, take the average head and fail, to be 8 feet.

The velocity of the skirts of the wheels is 1~ feel'per second, which is due to a fall of 27 inches. The water issues upon the wheel from under a head of 12 inches; its effluent velocity is, therefore+ 8 feet per second; bu~ the direction given to i~ by the t~,rm of the:aperture

+ Scc t h e 1able, p. It,!,'

!hr()u..h which it i*,me% is at an angle of about 45 degrees with dic hreas~ of'the xx heal, , f course, its .velocity in the dtreetmn m winch the skirt of (he wheel moves, eaimot be~more (han .~ feet per se. cond; but as the wheel moves at the rate of 1~ feet per s econG i( must expend some of its power in impressing its own veloci ty on the water. ~ The whole loss of power may I)e estimated t h u s : ~

Thevehmity oflhe wheel 12 feet per second, is acquired by water in falling, , g7 inches,

The water issues tm tile wlmel from under a head of I'2 im Its velocity in the requh'ed direction is 5" feet per sc-

cond~ which is due 1o a fall of 5~ in. The dilt~rence is so much lost~ viz, 6~ t i t he s

Totalloss 35,J inches ()r thus :~ ~ - - The ~ ehmilv of tile water in the required direction~ is tha t whMt

is duc lo a fall of !i.~ iuches. Imm/'diately m~ striking the wheel, it receives a velocity due to a

tilil of 27 inchc~,. The ditli:vc,ce, i,dicates the power expemled by the wheel9 in gi~, r"

il G it that ~clocity, - - ~1 ~ inehe~, The waler c<m~t s .. d~' whcd behm' the suvfiu:c of die

dam~ 1 ?. inche~

Total loss as before~ 55 :', hmht:s,

Thus it appeavs~ that of the whole power expended~ one third i~. lost by the excess of speed, and the ~ianner in which the water is infl'oduced into tile buckets: and two thirds are etFectually applied to lhe work.

Tim height through which file water is raised, f,'om tim dam io the res:'rvoir, is !)6 feet'~ the water which raises if. fidls 8 feeL3 thc.l'cfore~ ,'mppushl g that all tile power could be etl'cctually used, aud na loss ,c4stahle~l on account of leakage, fl'iction, &e. lg gal lons o n the wheels descending 8 f'ee{, shouid raise 1 gallon to t h e resevvoir, 96 l>eI; whereas, every gallon that reaches the reservoi h costs an expen- diture of beh{'een 50 and ,10 gallons from tile dam. Suppose the average expemllture % be :;6 gallons, to raise I gallon; then~ but one-thiL.d of this power is accounted for at lhe reservoir- and as I have shown that om'Mhird is lost by the excessive ve loc i ty of the wheel, &c. the remaining ooe.-third must be charged to ti'ictim~, leak.. age, &c' This last tl'~{rd, however, is one half of the effective power.

1 have made a calculation of tile distances, and velocities~ attained h" fifllin.'~ . ~, bodies,, in various, f'aclion d . ]torts of a. second, which i~,. Amt: introduced, tot the mformatmn ofthosepraeheal~ and theoretical, [ ' ~:~;i ( ~'tsV; ~r .~ t~:t~'C avoi&d I e la ) m ~f doing i( fiw lhentst:lves.

I;vc~_'~. ,,,if:alter at Fah' Mount l/Itt~;I have n(~tm,,:,,I the nols;c prodttced br {Lc l)cr,*!~;G,,~ ,,{'!h. i!,, s of~ }c .vhc,ds, ,p,~ ~1,~: ,v ,-,r ,.~(:}.i~.. I11o bllckc)~.

On Water Birheels. 16t

i have IJroceeded on the following established data, ~iz, Heavy l]odies fall through a distance of 16 feet, in the first seeond~

at the end of which, they Mve acquired a velocity of 3~ feet per se. cond.--The velocity increases as the t imes . - -The distance increases as the squares of the times.

Time of Descent.

aq -

i f l£8tl~s °f a see '

4~32nds of a see.

1-4th of a see.

,X l : I I

11 ~3£ntls, do,

13 t 14 - 15 -

:" t f ialfofa sec.

18 - - 19 - - £ S~nds. do. e l I -

ilJ - 1,4ths of a sec.

25 1 ~6 - ~7 ~ - 28~o£nds . do,

50 - ,31 -

1 - Tseconds .

! 5 / - . , o 3 -

1 minute,

Vol., I V , ~ N o , 9.,-~SEvTc~nv, n, 1827.

Distance fallen. f t . inches. o o ~

- o o ~ - o o ~ - o o?~ - 0 O~ - o o }

o o} - o o~

o l ~ 0 5 o 4~ o I 0 1 0

I Jo~ 3

'2 7 ~

s 67~ 4 0 4 6{

- 5 O~

6 6 10~ 7 6# 8 S{ 9 0 9 9{

tO 6~ Jl 4{ 12 3 15 12 14 O~ 15 o~ 16 64

3600 14400 57600

Velocity attained per sec. ft. inches. 0 $ 0 6 0 9 1 1 5 1 6 1 9

5 4 5 6 7 8 9

10 11 19. 13 14 15 16 17 18 19 2O

- 21

2~ ~4 05 ~26 £7 08 £9 50 ,'31 5~ 64

" 4 8 0 960

19~0

£2

170 Edi lor ' s tteld3,J to J~lr. Genet.

"l'o deter,trine what proportion of a given water power, is lo~t by a given velocity of the wheel, it is only necessary to ascertain~ what (. . . . . .

hstance the water must descend to acquire that velocity. Then, this dista,ce compared with the whole fall, answers the question. Thus: suppose the whole fall to be 10 feet, antl the velocity of the wheel 4 feet per second ; this velocity is due to a fall of $ inches, or one-fortieth part of the whole fall, which is the proportion sought. Or, suppose the velocity to be hq feet per second, which is due to a fall of '2 feet 7~ inches,-then the loss is-rather more than one-fourth of the whole fall of 10 feet. But, it must be especially noted, that these estimates enlbrace the supposition, that the water issues upota the wheel in the direction of the motion of its skirt, and precisely at that distance below the surface of the dam, which answers to the velocity of the wheeh Inattentiml to this particular, is a very im- portant, and fi'equent, cause of loss. b . M .

• q~ffmadverslons on .air. Genet's Rqol v to " Remarks on his 3lemo- rial on the Upwvrd l,'orces of Fluids ; " with additional observations on the merits of that work. By the EnrroR.--[ Continusd fro'm p. ~l l .3

" L e a v e n o t .x w r e c k b e h i n d . "

Ix our last number we examined the high pretensions of Mr. Ge- net, to extensive infi)rmation on the subject of the steam-engine, and will now ask tl~e attention of our readers, to a few remarks upon his projected imi)rovement.~ in navigation and aerostation; and if we do not greatly mistake, we shall convince the phrenologists, that we have the organ of destructiveness completely develope~.

h - - - W e ad been led to anticipate a very formidable reply to our strictures, published in January last; I)r. Pascalis having, some time since informed a mutual fi'iend, that the proot~ of out- ignorance would be made to stand out in bold relief. The Doctor, we ap- prehended, wouhl continue to sustain the character which he had assumed, as the champion of his friend, against those who are " not even qualified to bestow either praise or censure;" many of our remarks having been elicited by the bold tone of his communication in Dr. Silliman's Journah Mr. Genet, however, informs us, that the task of defence devolves upon himself exclusively, from the de- termination of his friend " to observe only silence;" convinced~ no doubt, that the better part of valour, is discretion. The cause of our being thus sent to Coventry by the Dr. is set forth by Mr. G., who, •sl~eakin~ of our remarks, says, " But how great was my sur- prise, at !inding that nearly the whole of this new producfion'of his lien, was in a great measure calculated to involve in my proscription, our worthy friend DOeTOn. PASCALIS, Sgxlolt CENS01¢ oF TIlE STATE M E D I C A L S O C I E T Y OF ~.~-E'W YORK, AND PP, E S I D E N T OF T I I N AMEal- CAN BIi.ANCt-I OF THF, LINNJKAN SOCII~TY) and to hold us both up to