History of Montgomery County, Pennsylvania, Part 3

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901
Publication date: 1884
Publisher: Philadelphia, Everts & Peck
Number of Pages: 1534

USA > Pennsylvania > Montgomery County > History of Montgomery County, Pennsylvania > Part 3

Note: The text from this book was generated using artificial intelligence so there may be some errors. The full pages can be found on Archive.org (link on the Part 1 page).

"' NoaRITON, July 18, 1769.

"' DEAR SIR,-The inclosed is the best account I can give of the con- tacts as I observed them and of what I saw during the interval between them. I should be glad you would contract them, and also the other papers, into a smaller compass, as I would have done myself if I had known how. I beg you would not copy anything merely because I have written it, but leave out what you think superfluous.

"' I am, with great esteem and affection, "' Yours, etc., DAVID RITTENHOUSE. "' To Rev. Dr. Smith,'"

Extract from Duvid Rittenhouse's Report of the Transit of Venus, June 3, 1769, observed at the Nurriton Observatory .- "' Early in November, 1768, I began to erect an observatory, agreeable to the resolutions of the Ameri-

HISTORY OF MONTGOMERY COUNTY.

from the observatory to the State-House Square at Philadelphia. Mr. Rittenhouse having ascertained the latitude and longitude at the point with acknowl-

can Philosophical Society, but, through various disappointments from workmen and weather, could not complete it till the middle of April, 1769. I had for some time expected the use of an equal-altitude instru- ment from Philadelphia ; but finding I could not depend on baving it, I fell to work and matle one of as simple a construction as I could. March 20th the instrument was finished and put up ont of doors, the observa- tory not being yet ready.

"' I had for some weeks before this, however, with my 36 f. re- fractor, observed eclipses of Jupiter'e satellitee in such a manuer that, though my equal-altitude instrument was not finished, and conse- quently I could not set my time-piece to the true noou, I should, never- theless, be able to tell the time of those eclipses afterwards when the instruments should be ready. For this purpose I observed almost every fair evening the time by the clock when the bright star in Orion disap- peared behind a fixed obstacle, by applying my eye to a small sight-hole made through a piece of brass fastened to a strong post. Frout this time to May 20 the clock was altered several times, once taken down aud cleaned, removed back to the observatory, and regulated anew. Care was taken, however, to observe equal altitudee of the sun on the days preceding and following any visible eclipse of the Ist satellite, when the weather would permit. May 20, in the morning, the clock wae set up for the last time pretty near the mean time. It had no provision for preventing the irregularities arising from heat and cold, nor could I fiud leisure to apply any contrivance of this sort. This day I likewise put wires instead of hairs in the telescope of the equal-altitude instrument. The ill state of my health would not permit me to eit up at nights to take equal altitudes of the stars. I was, therefore, obliged to content myeelf with those of the sun only.'

"It has been mentioned before that it was on Thursday afternoon, June I, that Mr. Lukens and myself arrived at Norriton, with a design to continue with Mr. Rittenhouse till the transit should be over. The prospect before us was very discouraging. That day and several pre- cediug had been generally overcast with cloude and frequent heavy rains, a thing not very common for so long a period at that season of the year in this part of America. But by one of those transitions which we often experience here, on Thursday evening the weather became per- fectly clear, and continued the day following, as well as the day of the transit, in such a state of serenity, splendor of sunshine, and purity of atmosphere that not the least appearance of a cloud was to be seen. June 2 and the forenoon of June 3 were spent in making necessary preparations, such as examining and marking the foci of our several telescopes, particularly the reflector, with and without the micrometer. The reflector was also placed on a polar axis, and such supports con- trived for resisting the ends of the refractors as might give them a mo- tion as nearly parallel to the equator as such hasty preparations would ivlunit. Several diametere of the suu were taken, and the micrometer examiued by ench other methods as the shortnees of the time would ullow. The sun was so intensely brigbt on the day of the transit that, instead of using the colored glasses sent from England with the re- flector, I put on a deeply-smoked glass prepared by Mr. Lukens, which gave a much more beautiful, natural, and well-defined appearance of the sun's disk. The smoked glase was fastened on the eye-tube with a little beeswax, and there was no occasion to change it the whole day, ae there was not the least cloud or intermission of the sun'e splendor. Mr. Rittenhouse, in hie previone projection, bad made the first external contact to be June 3, 2 h. 11' for lat. 40º N., and long. 5h W. of Greon- wich. on a supposition of the eun's parallax being 8". He happened to be very near the truth, for at 2h 10' 33", mean time, the first external contact was at Norriton, lat. 40° 9' 56" N., and long. 5h 1' 31" West. Other calculations made it generally from 6' to 8^ later for the latitude and longitude. Though this calculation was not given to be entirely depended on, yet it was sufficient to make we keep what, in the sea phrase, would be called a good look-out; and therefore at one o'clock we took off the micrometer, which had been fitted to the reflector with a power of 95, and adjusted it to distinct vision, with the same power to observe the contacts, and during the hour that was to intervene from one to two we resolved to keep an alternate watch through the reflector on that half of the sua's limb where Venus was certainly expected to touch, while the others not thus employed were fixing what more remained to be done, as follows, viz. : First, That each of us might the better exercise our own judgment without being influenced or thrown into any agitation by the

edged precision, and his reputation for exactness in all astronomical observations and calculations being duly credited in scientific and official circles in this

others, it wae agreed to transact everything by signals, and that one should not know what another was doing. The situation of the tele- scopes, the two refractors being at some distance without the observe- tory, and the reflector within, favored this design. Secondly, two per- sons, Mr. Sellers, one of our committee, and Mr. Archibald McClean, both well accustomed to matters of this kind, were placed at one window of the observatory, to count the clock and take the signal from Mr. Ln- kens. Two of Mr. Rittenhouse'e family, whom he had often employed to count the clock for him in hie observations, were placed at another window to take his signal. My telescope was placed near the clock, and I was to count ite beats and eet down my own time. These prelim- inaries being settled, we prepared at two o'clock to sit down to our re- spective telescopes, or, I should rather say, lie down to the refrectors, on account of the enn's great height. As there was n large concourse of the inhabitants of the county, and many from the city, we were appre- hensive that our scheme for silence would be defeated by some of them speaking when they should see any of the signals for the contacts, and therefore we found it uecessary to tell them that the success of our obser- vation would depend on their keeping a profound silence till the contacts were over. And, to do them justice, during the 12' that ensued there could not have been a more eolemn pause of silence and expectation if each individual had been waiting for the sentence that was to give him life or death. So regular and quiet was the whole that, far from hear- ing a whisper or word spoken, I did not even hear the feet of the count. ers who passed helind me from the windows to the clock, and was sur. prised, when I turned from my telescope to the clock, to find them all there before me, counting up their seconds to an even number, ns I im- agined, from the deep silence, that my associates had yet seen nothing of Venue. As the contacts are among the most essential articlee rela- tive to this phenomenon, it is material, before we set down the timee, to give a particular account of the mauper in which they were observed and the circumstances attending them."

Mr. Rittenhouse's Account of the Contacts .- " At 2h Il' 39" per clock, the Rev. Mr. Barton, of Lancaster, who assisted me at the telescope, on re- ceiving my signal, as had been agreed, instantaneously communicated it to the countere at the window by waving a handkerchief, who, walk- ing softly to the clock, counting seconds as they went along, noted down their times separately, agreeing to the same second; and three seconds sooner than this, to the best of my judgment, was the time when the least impression made by Venus on the sun's limb could be seen by my telescope. When the planet had advanced about one-third of its diam- eter on the sun, as I was steadily viewing its progress, my sight was sud- denly attracted by a beam of light which broke through on thiet side of Venus yet off the sun. Its figure was that of a broad-based pyramid, situated nbout 40 or 45 degrees on the limb of Venus, from a line passing through her centre and the sun's, and to the left hand of that line as seen through my telescope, which inverted. About the same time the sun's light began to epread round Venus on each side from the points where their limbs intersected each other. As Venus advanced the point of the pyramid still grew lower, its circular base wider, until it met the light which crept round from the points of intersection of the two limbs, so that when half the planet appenred on the eun, the other half yet off the sun was entirely surrounded by a semicircular light, best defined on the side next to the body of Venus, which continually grew brighter till the time of the internal contact. Imagination cannot form anything more beautifully serene and quiet than was the nir during the whole time, nor did I ever see the sun's limb more perfectly defined or more free from any tremulous motion, to which his great altitude undoubt- edly contributed much. When the internal contact, as it is called, drew nigh, I foresaw that it would be very difficult to fix the time with any certainty, on account of the great breadth and brightness of the light which surrounded that part of Venus yet off the sun. After some cou- sideration I resolved to judge us well as I could of the coincidence of the limbs, and accordingly gave the signal for the internal contact at 2h 28' 45" by the clock, and immediately began to count seconds, which any one who has been accustomed to it may do for a minute or two pretty near the truth. In this manner I counted no less than 1' 32" before the effect of the atmosphere of Venue on the eun'e limb wholly disappeared, leaving that part of the limb as well defined as the rest. From this I concluded that I had given the internal contact too soon, and the times given by the other observers at Norriton confirm me in this opinion."

O.W'ER

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MAP OF MONTGOMERY COUNTY, PENNA

JAfiles per Inch

NORTH COVENTRY

EASTY olimtrick Stu

E LOT ENHAM

PHILA

HAVERFORD

FRANCONIAseron

Projection of the Tranfil of Vins, over the Sun as observed at. Vorriton in Profileand gone 3 1769.

at 2 29 55'

at 2 19

Fig.3.

Fig. 2

ats 2.301053"

2 52 7

3 8"6

4 46.67

5.10.75

$ 14.5

5 15 3.

5 13 17

1 8.93

+ 29 7

+ 18 58

3 57 38

3 44. 66

'9 32 47 3 28 76

7 4 4.57

Line Paraliet to the Equator

10 14 74

Line Parallel to the Equateur

18.0.08

Fiq 9

Fuj 7

A 31

80 29 28

B 1220- 1050 E

Reduced to this Scale by T.Smith

Heury Darkens fiulpt

Delineated by David Rittenhouse todouble the above foule

7 57. 6

1 4

Fig.4.

Fig.5 012"B 15

The l'ha fes Figli Bare those notes by'ill : Hieltenhimuse in his Account of the Contacts Fig + 5 are the Phages noted by 1)" Smith in his (lecount and Füg 2.5 are also nated by I" Lukens .

AB THE

True Transit lainte

TOPOGRAPHY.

country and iu Europe, he was selected to report the difference of latitude and longitude between the " Norriton Observatory" and the State-House Square at Philadelphia, and harmonize the work with that of Mason and Dixon's Observatory at the south point of said city.

"ACCOUNT OF THE TERRESTRIAL MEASUREMENT OF THE DIFFERENCE OF LONGITUDE AND LATITUDE BETWEEN TILE OBSERVATORIES OF NORRITON AND PHILADELPHIA.

" To the American Philosophical Society, etc. :

"GENTLEMEN,-Agreeable to the appointment you made (at the request of the Astronomer Royal), Mr. Lnkens, Mr. Rittenhouse, and myself, furnished with proper instruments, met at Norriton, early on Monday, July 2d, for the above service, and took to our assistance two able and experienced surveyors, viz. : Mr. Archibald MeClean and Mr. Jesse Lukens. The first thing we did was accurately to ascertain the varia- tion of our compass, which we found 30 8' by Mr. Rittenhouse's meridian line. We then carefully measured our chain, and adjusted itto the exact standard of GG feet. In the execution of the work, whenever the in- strument was duly set, each course was taken off and entered down sep- arately by three different persons, who likewise kept separate accounte of all the distances, and superintended the stretching of every chain, and the leveling and plumbing it whenever there was any ascent or de- scent in the road. July 4th we finished the eurvey, and Mr. McClean, Mr. Jesse Lukens, and myself then agreed to bring out the difference of latitude and departure separately on each course and distance to four or five decimal places ; and there was so great an agreement in this part of the work when executed that we lind all the same resulte to a few links, and the whole was at last brought to agree ie every figure by comparing the few places where there was any difference, which scarce ever went further than the last decimal place. Mr. McClean and Mr. Lukens took the trouble to bring out their work by multiplying each distance by the natural sine of the course to the radius unity for the departure, and by the co-sine for the latitude. Mine was done by Rob- ertson's tables, and the following results obtained :

Distances.

Northing.

Southing.

Easting.

Westing.

Chains, Links. 1630.79

00.1447

1205.8095 00.1447

891.3616 39.5180

39.5180

Total Southing

1205.6648

851.8436 Total Easting.

Chains. 1205.6648

Log. 3.0812265 2.9303599

To tang. of E N A, the course 35º 14' 33".08 of the ...

9,849I334

Aod sine of 35º 14' 33".08.

9.7612048

To rad. A8 851.8436.

2 9303599

To NE. the distance in a straight line= 1476.2336 chains

But the course of N E being .. 35° 14' 33" E., With respect only to N A, the magnetic fourth, add the variation 3º 8' 0'

Which gives.

38° 22' 33" E. for the course of N E with respect to N S, the true meridian.

" So that the true course aod distance from Norritoa Observatory to Philadelphia Observatory in a straight line, N E, is S. 38° 22' 33" E. 1476,2336 chains.

" Then rad 10

To co-sine of. 38° 22' 33" 0.8942913

As NE

1476.2336

3.1691551

To N S true diff. of lat

II57.3013

3.0634464

And rad

To sine of.

38° 22' 33" 9.7929G37

As NE.

1476.2336 3.1691551

To S E, true diff. of long .. 916.4713

2 9621188

" Thins we have-

" Norriton Observatory from Philadelphia Observatory :

Chains. Feet.

North 1157.30 == 76381.8 =12'35".7 diff. of lat.

West 916.47 = 60487.02=00' 52" of time=13' diff. of longitude ==

9'.95 of a great circle or geographical mile.

" But the observatory in State-House Square, with respect to the fourth part of the city of Philadelphia (to which Messrs. Mason and Dixon refer their observation), is :

Chains. Feet. N. 40.0685 = 2644.5 =26".16 diff. of lat. W. 28.7695 =1898.8 == 1",6 of time.

" Therefore Norriton Observatory, with respect to the southernmost poiot of Philadelphia, is:

Chaios. Feet. North 1157.30 + 40.0685 == 1197.3685 == 79,026.3 == 13' 01".86 diff. ef lat.

West 916.47 + 28.7695 = 945.2395 =62,385.8 == 00' 53".6 of time.

" Hence by the above measurement and work we get Norriton Observa- tory 52" oftime west of the observatory in the State-House Square, which is exactly what we got by that excellent element, the external contact ef Mercury with the sun, Nov. 9, 1769. The internal contact gave it some- thing more, owing, no doubt, to the difference that will arise among oh- servers in determining the exact moment when the thread of light is completed ; and the mean of all our other observations gives the differ- ance of meridians between Norriton and Philadelphia only 4" of time more than the terrestrial measuremeat and the external contact of Mer- cury gave it, which may be taken as a very great degree of exactness for celestial observations, if we consider that the difference of meridians between the long-established observatories of Greenwich and Paris, as Mr. De La Lande writes, Nov. 18, 1762, was not then determined within 20" of time; for he says, 'Some called it 9' 15", others 9' 40", but that he himself commonly used 9' 20", though he could not tell from what observations it was deduced.' And it may be needless to add that & short distance is es liable to the differences arising from the use of in- struments in celestial observations as a greater one. Nevertheless, if we apply the difference of meridians between Philadelphia and Norriton got by this measurement (viz., 52" instead of 56") to the Rev. Mr. Ewing's collection of Jupiter's satellites, rejecting those of the 2d sat., and also the immersions of May 5th, as too near the oppositioo, we shall get Philadelphia 5h. 0' 37" and Norriton 5h. 1' 29" west freio Green- wich. This result is what ought to arise from a diminution of 4" of time in the difference of meridians by dividing that difference, and bringing the meridian 2" more west and the other 2" more east, and we believe future observations will confirm this as exceeding near the truth."

"The latitude of Norriton comes out by the meas- urement 25".09 less north, with respect to the south- ernmost point of the city of Philadelphia, than Mr. Rittenhouse's observations give it ; and if the latitude of that point of the city be taken, as fixed by Messrs. Mason and Dixon, at 39º 56' 29".4, then the lat. of Norriton (neglecting fractions of seconds) will be 40° 9' 31", instead of 40° 9' 56". However, as both were fixed by celestial observations and experienced men,

" Then N A, dif. of lat .. To A E, depart ..

851.8436

As rad.

3.1691551

HISTORY OF MONTGOMERY COUNTY.

the small difference ought perhaps to be divided; and il a mean be taken to reconcile it with the terrestrial measurements, the lat. of the south point of Philadel- phia would be 39º 56' 42"", and that of Norriton 40° 9' 43". But as Mr. Rittenhouse had only Sisson's two and a half feet quadrant, and Messrs. Mason and Dixon were furnished with a complete astronomical sector, and did their work to fix the lincs of two prov- inces, it may be thought that their determination is most to be relied upon. Nevertheless, the whole dif- ference of 25" in the celestial arc is so inconsidera- ble as not to give 40 chains on the surface of the earth. All the results in the above work are got without any sensible error, by plain trigonometry, as the different arcs are so very small. In estimating the length of a degree to deduce the difference of latitude between the two observations, the spheroidal figure of the earth was taken into consideration, and the degree measured by Messrs. Mason and Dixon, in mean latitude 39º 12',-363,771 feet,-was made the standard, which being lengthened in the ratio of 59.7866 to 59.8035, gave 363,874 for a degree of the meridian in the inean latitude between Philadelphia and Norriton, which is only 103 feet more than the deg. in lat. 39º 12', and makes but a fraction of a second difference in the latitude, so that it might have been disregarded. With respect to seconds of time in longitude, no sensible difference can be obtained in the small difference of about 11 miles, whether we consider the earth as a sphere or spheroid. In bring- ing out the 52"' of time diff. of long., a degree of the equator was taken in proportion to Messrs. Mason and Dixon's degree of the merid. in lat. 39''.12, in the ratio of GO to 59.7866 (agreeable to Mr. Simspon's table), which gave 365,070 for a degree of the equator. By taking a degree of longitude as fixed at the middle point by Mr. Maskelyne in lat. 38° 7' 35"", and saying as the co-sine of that lat. is to co-sine of mean latitude between Philadelphia and Norriton, so is the length of a degree of long. at the middle point (viz., 284,869.5 feet) to the length of a degree in mean lat. between Norri- ton and Philadelphia, the result was got 52".13, being only thirteen hundredth parts of a second more."

Philadelphia, Aug. 17, 1770, William Smith, Nor- riton Observatory, N. Latitude, 40° 9' 43''.

NOTE .- The true latitude and longitude of Phila- delphia we give from a compilation made by Prof. B. A. Gould for one of the numbers of "The American Ephemeris and Nautical Almanac." The data are determined for the observatories in each case (Inde- pendence Hall being lere taken) :

PHILADELPHIA, N. Latitude, 39º 57' 7.5". (MS. communication from Prof. Kendall) : Longitude E. from Washington (U. S. Coast Survey) :

By 5 sets Eastern clock-signals 8. By Western

33.66

33.60

Mean . 7 33.63

The mean, by comparison with the next East station (Jersey City), is 7 33.64

Hence the longitude in arc is 358° 6' 35.4'' from Washington, and from Greenwich, 75° 9' 23.4''.1

CHAPTER II.

ORES, MINERALS, AND GEOLOGY OF MONTGOMERY COUNTY.

BY PROFESSOR OSCAR C. S. CARTER, CENTRAL HIGH SCHOOL, PHILADELPHIA.

Gold .- The precious metals have been found throughout Montgomery County, but in such small quantities that their occurrence is more of scientific interest than of any practical value. Gold occurs disseminated throughout the azoic rocks, the oldest rocks with which we are acquainted. It is also found in the sands of rivers or in alluvial deposits which have been formed by the weathering and disintegra- tion of the oldest formations. Southern Montgomery County, from Philadelphia as far north as Conshio- hocken, is made up almost entirely of strata of the oldest rocks, but only traces of gold have been found,

1 On July 5, 1773, the Right Honorable the Earl of Dartmouth, who was at that time Colonial Secretary (he had succeeded Lord Hillsbor- ough one year before) in the cabinet of George III., wrote to the Deputy Governor of l'eunsylvania (John Penn, the son of Richard Penn, who was the fifth child of William Penn by his second wife, Hannah Callow- hill) propounding certain " Heads of Enquiry relative to the present State and Condition" of Pennsylvania. The answers to these inquiries were transmitted to Lord Dartmouth under date of Jan. 30, 1775. In the communication the following occurs: " The City of Philadelphia, sit_ uated near the Conflux of Delaware and one of its chief Branches, the Schuylkill, is the most considerable Town in the Province, or indeed in North America. The State-House in this City lies in North Latitude, 39º 56' 53""; its Longitude from the Royal Observatory at Greenwich, computed West, 75º 8' 45"; or, in time, 5 hours and 35 seconds. Thie Latitude and Longitude were both fixed by accurate astronomical Ob- servation at the Traveit of Venus, 1769." In the Journal of Mason and Dixon, November, 1763, we learn that these enrveyors established an observatory in the southern part of Philadelphia, in order to find the starting-point of the parallel which they were to run off. Their point of departure was " the most Southern part of Philadelphia," which they ascertained to be the north wall of a house on Cedar Street, occupied by Thomas Plumstead and Joseph Huddle, and their observatory must have been immediately adjacent to this. The latitude of this point they de- termined to be 39º 56' 29" north. In 1845, when the northeast corner- stone of Maryland could oot be found (it had been undermined by a freshet, and was then taken and built into the chimney of a neighbor- ing farm-house), the Legislaturee of Maryland, Pennsylvania, and Dela- ware appointed a joint commission, who employed Col. Graham, of the United States Topographical Engineers, to review Mnson and Dixon'e work so far us was requisite in order to restore the displaced corner. Col. Graham, in the course of his measurements, determined the latitude of the Cedar Street observatory to be 39º 56' 37.4" north. This is 8.3" more than the latitude given by Mason aod Dixon. If we add the dis- tance from Cedar Street to Chestnut Street, 2650 feet, we have for Inde- pendence IIall latitude ne determined by Mason and Dixon, 39º 56' 55"; 88 determined by Col. Graham, 39º 57' 03". The elight variation in these calculations is surprising. That reported by Governor Penn may have been based upon data differing from those of the surveye of 1761 and of Mason and Dixon. The grentest variation, however, is only about 1200 feet, or less than the fourth of a mile ; the least is only 200 feet .- Scharf's History of Philadelphia.

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History of Montgomery County, Pennsylvania, Part 3

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901 Publication date: 1884 Publisher: Philadelphia, Everts & Peck Number of Pages: 1534

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901
Publication date: 1884
Publisher: Philadelphia, Everts & Peck
Number of Pages: 1534