{ "id": "64d548b22e877fc27b23f6b1de1dca3c20c7f70e", "text": "These may suffice to prove, that Mr. Gascoigne's micrometer was not a mere thing in embryo, but brought to a good degree of perfection above 40 years before that of the French gentlemen was ever so much as mention'd. I am,\n\nSIR,\n\nRed-lion street, Clerkenwell, Your very humble servant,\nMay 10, 1753.\n\nJ. Bevis.\n\nXXX. Observations of the Transit of Mercury over the Sun, May 6, 1753; by Mr. J. Short, F. R. S.\n\nRead May 17, 1753.\n\nTHE instrument prepared for these observations was a reflecting telescope, of two feet focal length, of the Gregorian form, magnifying about 65 times, and so constructed in its machinery as to move in a plane parallel to the horizon, and also, when required, to move in a plane parallel to the equator. This telescope had two eye-pieces, each a combination of two glasses, viz. one eye-piece for the horizontal motion, with wires at right angles to one another, the wires being between the\nthe glasses, and one of the wires placed parallel to the horizon, and consequently the other was vertical; the other eye-piece was also a combination of two glasses, and adapted to a micrometer, the glasses being placed between the wires of the micrometer and the eye of the observer, and was to be used when the telescope moved in a plane parallel to the equator.\n\nMr. Short's house, in Surry-street, being so situated as not to see the sun at rising, the Rev. Dr. Birch, Secretary of the Royal Society, was pleased to allow us the use of his leads on his house in Norfolk-street, from whence we should be enabled to see the sun soon after he rose. We chose the doctor's leads, that we might not be far from Mr. Short's clock, which was easily within call, in order to compare a second-watch, which we made use of, with the clock, at every observation.\n\nAbout half an hour after 4 o'clock in the morning of the 6th of May, Dr. Bevis and Mr. Short went to Dr. Birch's house, where the following observations were taken with the above reflecting telescope moving parallel to the horizon, and the eye-piece with the wires at right angles; Dr. Bevis observing, and Mr. Short writing down the times.\n\nBy Mr. Short's clock.\n\n| h | m | s | Description |\n|---|----|----|--------------------------------------|\n| 5 | 20 | 25 | ◯ upper limb at the horizontal wire. |\n| 20| 29 | | ◯ preceding limb at the vertical wire. |\n| 22| 9½ | | ♀ center at the vertical wire. |\n| 22| 33 | | ♀ center at the horizontal wire. |\n| 23| 19 | | ◯ subsequent limb at the vertical wire. |\n| 24| 0 | | ◯ under limb at the horizontal wire. |\n\nB b II.\nBy Mr. Short's clock.\n\nII.\n5 25 24 ⊙ upper limb at the horizontal wire.\n25 27 ⊙ preceding limb at the vertical wire.\n5 27 5½ ⊙ center at the vertical wire.\n27 34 ⊙ center at the horizontal wire.\n28 17½ ⊙ subsequent limb at the vertical wire.\n29 0½ ⊙ lower limb at the horizontal wire.\n\nIII.\n31 45 ⊙ upper limb at the horizontal wire.\n31 55½ ⊙ preceding limb at the vertical wire.\n33 32 ⊙ center at the vertical wire.\n33 52½ ⊙ center at the horizontal wire.\n34 47 ⊙ subsequent limb at the preceding wire.\n35 20½ ⊙ under limb at the horizontal wire.\n\nIV.\n36 44½ ⊙ upper limb at the upper wire.\n36 54 ⊙ preceding limb at the vertical wire.\n38 29 ⊙ center at the vertical wire.\n38 49½ ⊙ center at the horizontal wire.\n39 45½ ⊙ subsequent limb at the vertical wire.\n40 18 ⊙ under limb at the horizontal wire.\n\nV.\n41 8 ⊙ upper limb at the horizontal wire.\n41 25 ⊙ preceding limb at the vertical wire.\n42 57½ ⊙ center at the vertical wire.\n43 13 ⊙ center at the horizontal wire.\n44 16 ⊙ subsequent limb at the vertical wire.\n44 39 ⊙ under limb at the horizontal wire.\n\nVI.\n47 45½ ⊙ upper limb at the horizontal wire.\n47 52½ ⊙ preceding limb at the vertical wire.\nBy Mr. Short's clock.\n\n5 49 23 ♀ center at the vertical wire.\n49 52 ♀ center at the horizontal wire.\n50 53½ ⊙ subsequent limb at the vertical wire.\n51 19 ⊙ under limb at the horizontal wire.\n\nVII.\n55 44¾ ⊙ upper limb at the horizontal wire.\n55 51½ ⊙ preceding limb at the vertical wire.\n57 19¾ ♀ center at the vertical wire.\n57 48 ♀ center at the horizontal wire.\n58 44 ⊙ subsequent limb at the vertical wire.\n59 15¾ ⊙ under limb at the horizontal wire.\n\nVIII.\n6 1 29 ⊙ upper limb at the horizontal wire.\n1 37½ ⊙ preceding limb at the vertical wire.\n3 4 ♀ center at the vertical wire.\n3 32½ ♀ center at the horizontal wire.\n4 31½ ⊙ subsequent limb at the vertical wire.\n4 58 ⊙ under limb at the horizontal wire.\n\nIX.\n5 31½ ⊙ upper limb at the horizontal wire.\n5 39½ ⊙ preceding limb at the vertical wire.\n7 5 ♀ center at the vertical wire.\n7 33¾ ♀ center at the horizontal wire.\n8 33 ⊙ subsequent limb at the vertical wire.\n9 1½ ⊙ under limb at the horizontal wire.\n\nX.\n13 42½ ⊙ upper limb at the horizontal wire.\n13 45 ⊙ preceding limb at the vertical wire.\nBy Mr. Short's clock.\n\n6 15 8 ♀ center at the vertical wire.\n15 41 ♀ center at the horizontal wire.\n16 39 ⊙ subsequent limb at the vertical wire.\n17 8½ ⊙ under limb at the horizontal wire.\n\nXI.\n18 17 ⊙ upper limb at the horizontal wire.\n18 22½ ⊙ preceding limb at the vertical wire.\n19 44½ ♀ center at the vertical wire.\n20 17½ ♀ center at the horizontal wire.\n21 17 ⊙ subsequent limb at the vertical wire.\n21 44½ ⊙ under limb at the horizontal wire.\n\nAbout half an hour after 6, Dr. Bevis and Mr. Short went to Mr. Short's house, the sun then shining into his windows, in order to be near the clock, where the following observations were made in the same manner as before, Dr. Bevis observing, and Mr. Short writing down the times, in the presence of the right honourable James Earl of Morton, a fellow of this Society.\n\nBy Mr. Short's clock.\n\nXII.\n7 1 32 ⊙ upper limb at the horizontal wire.\n1 43½ ⊙ preceding limb at the vertical wire.\n2 50 ♀ center at the vertical wire.\n3 24½ ♀ center at the horizontal wire.\n4 39 ⊙ subsequent limb at the vertical wire.\n4 57 ⊙ under limb at the horizontal wire.\n\nXIII.\nBy Mr. Short's clock.\n\nXIII.\n\n7 6 35\\(\\frac{1}{2}\\) ⊙ upper limb at the horizontal wire.\n6 41\\(\\frac{1}{2}\\) ⊙ preceding limb at the vertical wire.\n7 45\\(\\frac{1}{2}\\) ♀ center at the vertical wire.\n8 28\\(\\frac{1}{2}\\) ♀ center at the horizontal wire.\n9 35\\(\\frac{1}{2}\\) ⊙ subsequent limb at the vertical wire.\n10 0\\(\\frac{1}{2}\\) ⊙ subsequent limb at the horizontal wire.\n\nThe telescope, which hitherto moved parallel to the horizon, was now altered, to move parallel to the equator, and the eye-piece with the micrometer was applied, about half an hour after seven o'clock, Mr. Short observing, and Dr. Bevis writing down the times of observation.\n\n7 31 33 distance between the center of ♀ and ⊙'s under limb = 19 rev. 6 parts of the micrometer.\n\n36 7\\(\\frac{1}{2}\\) ⊙'s preceding limb at the horary wire.\n36 56\\(\\frac{1}{2}\\) ♀ center at the horary wire.\n37 56 ♀ center distant from the ⊙'s upper limb = 34 rev. 14 parts.\n\n41 33 ⊙'s preceding limb at the horary wire.\n42 21\\(\\frac{1}{2}\\) ♀ center at the horary wire.\n43 21 ♀ center distant from the ⊙ upper limb = 34 rev. 23 parts.\n\n44 34 ⊙ preceding limb at the horary wire.\n45 21\\(\\frac{1}{2}\\) ♀ center at the horary wire. At the same time ♀ distance from ⊙ upper limb = 34 rev. 29 parts.\n8 4 25 ⊙ preceding limb at the horary wire.\n5 7 ♀ center at the horary wire. At the same time ♀ distance from ⊙ upper limb = 35 rev. 29 parts.\n6 37½ ⊙ subsequent limb at the horary wire.\n\n16 25¾ ⊙ preceding limb at the horary wire.\n17 6 ♀ center at the horary wire. At the same time ♀ distance from ⊙ upper limb = 36 rev. 19 parts.\n18 39 ⊙ subsequent limb at the horary wire.\n\n44 1½ ⊙ preceding limb at the horary wire.\n44 35½ ♀ center at the horary wire. Presently after ♀ distance from ⊙ upper limb = 37 rev. 28 parts.\n46 14 ⊙ subsequent limb at the horary wire.\n\nThe sun's diameter perpendicular to the equator was taken in the micrometer of the reflecting telescope at 7h 25', and found to be = 53 rev. 13 parts, = 31' 50''.\n\nThe sun's diameter perpendicular to the equator was taken in the micrometer of the 12 foot refracting telescope (which belonged to the late Mr. Graham) at about half an hour after 9 o'clock, and found to be equal to 51 rev. 14 parts, = 31' 51''.\n\nNote, The reflector's micrometer has 35 parts in one revolution of the screw; and the refractor's micrometer has 37 parts in one revolution of the screw.\n\nMr.\nMr. Short observed the last internal contact of mercury with the sun, with a four foot focal length reflector, magnifying about 135 times, at $10^h\\ 5'7''$ by the clock, uncertain to 2 or 3''; and the total egress at $10^h\\ 7'42''$ by the clock; uncertain to 5 or 6'', the air then undulating thro' thin clouds.\n\nDr. Bevis observed the last internal contact with a two foot focal length reflector, magnifying about 65 times, at $10^h\\ 5'$, and the total egress at $10^h\\ 7'38''$, by the clock.\n\nMr. Siffon, at Beaufort-Buildings in the Strand, observed the total egress at $10^h\\ 7'43''$, by Mr. Short's clock, thro' a five foot refracting telescope.\n\nMr. Bird, at his house in York-Buildings, observed the last internal contact at $10^h\\ 4'57''$; and the total egress at $10^h\\ 7'43''$, by Mr. Short's clock, thro' a nine inch focal length reflector.\n\nMr. Smeaton in Furnival's-Inn-Court, Holborn, observed the total egress at $10^h\\ 8'30''$, by Mr. Short's clock, thro' a six foot refracting telescope. — He suspects his time some seconds too late, a cloud having just passed off the sun, when he perceived Mercury was gone.\n\nMr. Canton, in Spital-square, observed the total egress at $10^h\\ 8'12''$, mean time, thro' a reflecting telescope, three feet focal length.\n\nMr. Short's house in Surrey-street is 26'' of time west of the royal observatory at Greenwich.\n\nN.B. Mr. Short's clock, by which these observations were made, was found to be 28'' slower than mean time: but, for more satisfaction, here are the sun's passages over the meridian, taken by the transitory.\n\nMay\nMay 7, Sun's preceding limb passed the meridian at $11^h\\ 54^m\\ 38^s$\nSubsequent limb passed the mer. $11^h\\ 56^m\\ 51^{1/2}$\n\nMay 8, Sun's preceding limb passed the meridian, at $11^h\\ 54^m\\ 34^{1/2}$\nSubsequent limb passed the meridian, at $11^h\\ 56^m\\ 47^{1/2}$\n\nN. B. This clock, by repeated observations, was not found to have varied above $1''$ since the 22 of February last to the day of observation.\n\nIn the observatory of the right honourable the Earl of Macclesfield, at Shirburn-Castle in Oxfordshire, the total egress was observed at $10^h\\ 8'\\ 11''$, apparent time. Latitude of Shirburn-Castle is $51^\\circ\\ 39'\\ 25''$, and its longitude is $4'\\ 0''$ of time, west of Greenwich observatory.", "source": "olmocr", "added": "2026-01-12", "created": "2026-01-12", "metadata": { "Source-File": "/home/jic823/projects/def-jic823/royalsociety/pdfs/105144.pdf", "olmocr-version": "0.3.4", "pdf-total-pages": 10, "total-input-tokens": 14622, "total-output-tokens": 3579, "total-fallback-pages": 0 }, "attributes": { "pdf_page_numbers": [ [ 0, 0, 1 ], [ 0, 920, 2 ], [ 920, 2595, 3 ], [ 2595, 3751, 4 ], [ 3751, 4810, 5 ], [ 4810, 5918, 6 ], [ 5918, 7165, 7 ], [ 7165, 8301, 8 ], [ 8301, 9879, 9 ], [ 9879, 10581, 10 ] ], "primary_language": [ "en", "en", "en", "en", "en", "en", "en", "en", "en", "en" ], "is_rotation_valid": [ true, true, true, true, true, true, true, true, true, true ], "rotation_correction": [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ], "is_table": [ false, false, false, false, false, false, false, false, false, false ], "is_diagram": [ false, false, false, false, false, false, false, false, false, false ] }, "jstor_metadata": { "identifier": "jstor-105144", "title": "Observations of the Transit of Mercury Over the Sun, May 6, 1753; by Mr. J. Short, F. R. S.", "authors": "J. Short", "year": 1753, "volume": "48", "journal": "Philosophical Transactions (1683-1775)", "page_count": 10, "jstor_url": "https://www.jstor.org/stable/105144" } }