part15-第7部分

快捷操作: 按键盘上方向键 ← 或 → 可快速上下翻页 按键盘上的 Enter 键可回到本书目录页 按键盘上方向键 ↑ 可回到本页顶部! 如果本书没有阅读完，想下次继续接着阅读，可使用上方 "收藏到我的浏览器" 功能 和 "加入书签" 功能！


dry；　or　7/8　of　a　ton　liquid。

　　　　　　　　Dime　=　。1　would　be　about　3。5　cubic　feet；　2。8　bushels；　or　about

7/8　of　a　barrel　liquid。

　　　　　　　　Cent　=　。01　about　50　cubic　inches；　or　7/8　of　a　quart。

　　　　　　　　Mill　=　。001　=　。5　of　a　cubic　inch；　or　2/3　of　a　gill。




　　　　　　　　To　incorporate　into　the　same　system　our　weights　and　coins；　we

must　recur　to　some　natural　substance；　to　be　found　everywhere；　and　of

a　composition　sufficiently　uniform。　　Water　has　been　considered　as　the

most　eligible　substance；　and　rain…water　more　nearly　uniform　than　any

other　kind　found　in　nature。　　That　circumstance　renders　it　preferable

to　distilled　water；　and　its　variations　in　weight　may　be　called

insensible。




　　　　　　　　The　cubic　unit　of　this　=　。1　would　weigh　about　2；165　lbs。　or　a

ton　between　the　long　and　short。

　　　　　　　　　　　　　　　　　The　Dime　=　。1　a　little　more　than　2。　kentals。

　　　　　　　　　　　　　　　　　　　　　Cent　=　。01　a　little　more　than　20　lb。

　　　　　　　　　　　　　　　　　　　　　Mill　=　。001　a　little　more　than　2　lb。

　　　　　　　　　　　　　　　　　Decimmil　=　。0001　about　3　1/2　oz。　avoirdupoise。

　　　　　　　　　　　　　　　　Centimmil　=　。00001　a　little　more　than　6　dwt。

　　　　　　　　　　　　　　　　Millionth　=　。000001　about　15　grains。

　　　　　　　　　　　Decimmillionth　=　。0000001　about　1　1/2　grains。

　　　　　　　　　　Centimmillionth　=　。00000001　about　。14　of　a　grain。

　　　　　　　　　　　　　　　　Billionth　=　。000000001　about　。014　of　a　grain。




　　　　　　　　With　respect　to　our　coins；　the　pure　silver　in　a　dollar　being

fixed　by　law　at　347　1/4　grains；　and　all　debts　and　contracts　being

bottomed　on　that　value；　we　can　only　state　the　pure　silver　in　the

dollar；　which　would　be　very　nearly　23　millionths。




　　　　　　　　I　have　used　loose　and　round　numbers　（the　exact　unit　being　yet

undetermined）　merely　to　give　a　general　idea　of　the　measures　and

weights　proposed；　when　compared　with　those　we　now　use。　　And　in　the

names　of　the　subdivisions　I　have　followed　the　metrology　of　the

ordinance　of　Congress　of　1786；　which　for　their　series　below　unit

adopted　the　Roman　numerals。　　For　that　above　unit　the　Grecian　is

convenient；　and　has　been　adopted　in　the　new　French　system。




　　　　　　　　We　come　now　to　our　last　question；　in　what　form　shall　we　offer

this　metrical　system　to　the　world？　　In　some　one　which　shall　be

altogether　unassuming；　which　shall　not　have　the　appearance　of　taking

the　lead　among　our　sister　institutions　in　making　a　general

proposition。　　So　jealous　is　the　spirit　of　equality　in　the　republic　of

letters；　that　the　smallest　excitement　of　that　would　mar　our　views；

however　salutary　for　all。　　We　are　in　habits　of　correspondence　with

some　of　these　institutions；　and　identity　of　character　and　of　object；

authorize　our　entering　into　correspondence　with　all。　　Let　us　then

mature　our　system　as　far　as　can　be　done　at　present；　by　ascertaining

the　length　of　the　second　pendulum　of　45　degrees　by　forming　two

tables；　one　of　which　shall　give　the　equivalent　of　every　different

denomination　of　measures；　weights　and　coins　in　these　States；　in　the

unit　of　that　pendulum；　its　decimals　and　multiples；　and　the　other

stating　the　equivalent　of　all　the　decimal　parts　and　multiples　of　that

pendulum；　in　the　several　denominations　of　measures；　weights　and　coins

of　our　existing　system。　　This　done；　we　might　communicate　to　one　or

more　of　these　institutions　in　every　civilized　country　a　copy　of　those

tables；　stating　as　our　motive；　the　difficulty　we　had　experienced；　and

often　the　impossibility　of　ascertaining　the　value　of　the　measures；

weights　and　coins　of　other　countries；　expressed　in　any　standard　which

we　possess；　that　desirous　of　being　relieved　from　this；　and　of

obtaining　information　which　could　be　relied　on　for　the　purposes　of

science；　as　well　as　of　business；　we　had　concluded　to　ask　it　from　the

learned　societies　of　other　nations；　who　are　especially　qualified　to

give　it　with　the　requisite　accuracy；　that　in　making　this　request　we

had　thought　it　our　duty　first　to　do　ourselves；　and　to　offer　to

others；　what　we　meant　to　ask　from　them；　by　stating　the　value　of　our

own　measures；　weights　and　coins；　in　some　unit　of　measure　already

possessed；　or　easily　obtainable；　by　all　nations；　that　the　pendulum

vibrating　seconds　of　mean　time；　presents　itself　as　such　an　unit；　its

length　being　determined　by　the　laws　of　nature；　and　easily

ascertainable　at　all　times　and　places；　that　we　have　thought　that　of

45　degrees　would　be　the　most　unexceptionable；　as　being　a　mean　of　all

other　parallels；　and　open　to　actual　trial　in　both　hemispheres。　　In

this；　therefore；　as　an　unit；　and　in　its　parts　and　multiples　in　the

decimal　ratio；　we　have　expressed；　in　the　tables　communicated；　the

value　of　all　the　measures；　weights　and　coins　used　in　the　United

States；　and　we　ask　in　return　from　their　body　a　table　of　the　weights；

measures　and　coins　in　use　within　their　country；　expressed　in　the

parts　and　multiples　of　the　same　unit。　　Having　requested　the　same

favor　from　the　learned　societies　of　other　nations；　our　object　is；

with　their　assistance；　to　place　within　the　reach　of　our　fellow

citizens　at　large　a　perfect　knowledge　of　the　measures；　weights　and

coins　of　the　countries　with　which　they　have　commercial　or　friendly

intercourse；　and　should　the　societies　of　other　countries　interchange

their　respective　tables；　the　learned　will　be　in　possession　of　an

uniform　language　in　measures；　weights　and　coins；　which　may　with　time

become　useful　to　other　descriptions　of　their　citizens；　and　even　to

their　governments。　　This；　however；　will　rest　with　their　pleasure；　not

presuming；　in　the　present　proposition；　to　extend　our　views　beyond　the

limits　of　our　own　nation。　　I　offer　this　sketch　merely　as　the　outline

of　the　kind　of　communication　which　I　should　hope　would　excite　no

jealousy　or　repugnance。




　　　　　　　　Peculiar　circumstances；　however；　would　require　letters　of　a

more　special　character　to　the　Institute　of　France；　and　the　Royal

Society　of　England。　　The　magnificent　work　which　France　has　executed

in　the　admeasurement　of　so　large　a　portion　of　the　meridian；　has　a

claim　to　great　respect　in　our　reference　to　it。　　We　should　only　ask　a

communication　of　their　metrical　system；　expressed　in　equivalent

values　of　the　second　pendulum　of　45　degrees　as　ascertained　by　Messrs。

Borda；　Coulomb　and　Cassini；　adding；　perhaps；　the　request　of　an　actual

rod　of　the　length　of　that　pendulum。




　　　　　　　　With　England；　our　explanations　will　be　much　more　delicate。

They　are　the　older　country；　the　mother　country；　more　advanced　in　the

arts　and　sciences；　possessing　more　wealth　and　leisure　for　their

improvement；　and　animated　by　a　pride　more　than　laudable　（*）。　　It　is

their　measures；　too；　which　we　undertake　to　ascertain　and　communicate

to　themselves。　　The　subject　should　therefore　be　opened　to　them　with

infinite　tenderness　and　respect；　and　in　some　way　which　might　give

them　due　place　in　its　agency。　　The　parallel　of　45　degrees　being

within　our　latitude　and　not　within　theirs；　the　actual　experiments

under　that　would　be　of　course　assignable　to　us。　　But　as　a　corrective；

I　would　propose　that　they　should　ascertain　the　length　of　the　pendulum

vibrating　seconds　in　the　city　of　London；　or　at　the　observatory　of

Greenwich；　while　we　should　do　the　same　in　an　equi…distant　parallel　to

the　south　of　45　degrees；　suppose　in　38　degrees　29'。We　might　ask　of

them；　too；　as　they　are　in　possession　of　thestandards　of　Guildhall；　of

which　we　can　have　but　an　unauthentic　account；　to　make　the　actual

application　of　those　standards　to　the　pendulum　when　ascertained。　　The

operation　we　should　undertake　under　the　45th　parallel；　（about

Passama…quoddy；）　would　give　us　a　happy　occasion；　too；　of　engaging　our

sister　society　of　Boston　in　our　views；　by　referring　to　them　the

execution　of　that　part　of　the　work。　　For　that　of　38　degrees　29'　we

should　be　at　a　loss。　　It　crosses　the　tide　waters　of　the　Potomac；

about　Dumfries；　and　I　do　not　know　what　our　resources　there　would　be

unless　we　borrow　them　from　Washington；　where　there　are　competent

persons。




　　　　　　　　（*）　We　are　all　occupied　in　industrious　pursuits。　　They　abound

with　persons　living　on　the　industry　of　their　fathers；　or　on　the

earnings　of　their　fellow　citizens；　given　away　by　their　rulers　in

sinecures　and　pensions。　　Some　of　these；　desirous　of　laudable

distinction；　devote　their　time　and　means　to　the　pursuits　of　science；

and　become　profitable　members　of　society　by　an　industry　of　a　higher

order。










　　　　　　　　Although　I　have　not　mentioned　Philadelphia　in　these　operations；

I　by　no　means　propose　to　relinquish　the　benefit　of　observations　to　be

made　there。　　Her　science　and　perfection　in　the　arts　would　be　a

valuable　corrective　to　the　less　perfect　state　of　them　in　the　other

places　of　observation。　　Indeed；　it　is　to　be　wished　that　Philadelphia

could　be　made　the　point　of　observation　south　of　45　degrees；　and　that

the　Royal　Society　would　undertake　the　counterpoint　on　the　north；

which　would　be　somewhere　between　the　Lizard　and　Falmouth。　　The　actual

pendulums　from　both　of　our　points　of　observation；　and　not　merely　the

measures　of　them；　should　be　delivered　to　the　P