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[[left margin]] Experiment to prove that an object appears less thro' a dense medium than a rarer. which contradicts the received notion & the known rules of optics. [[/left margin]]
it be, as it sometimes happens, that they become fogs, and condense near the surface of the earth; in such a [[strikethrough]] situt [[/strikethrough]] situation the eye will see the moon as big as [[bold]]B [[/bold]]. When the eye is directed upwards to the moon in the meridian, the upper regions of the air abounding with condensation, it will see the moon as small as [[bold]]A [[/bold]]. The following experiment seems to confirm this hypothesis. Take a bason, and fill it with clear water: when so filled, put in half a crown or any piece of that size, and take it's apparent diameter, as it offers it to the eye from the bottom of the bason. When you have done this condense the medium of water with two or three spoon-fulls of red wine, milk, beer, or any other liquid, but not so much as to make the medium opaque, putting in so much only as will still keep it pellucid. In this case, and under these circumstances of consideration, to an attentive observer, the apparent diameter will be considerably lessened.
I don't know that this phӕnomenon, so much the wrangle of [[insertion]] the [[/insertion]] schools at [[underline]] Cambridge [[/underline]], has been accounted for on these principles. May your philosophical correspondents improve upon this hint, and endeavour to draw aside the veil that has hitherto concealed this truth from the sons of science.
[[left column]] [[underline]] High Wycombe
Bucks. Sept. [[/underline]] 9th. [[/left column]]
[[middle column]] [[underline]] I am yours [[/underline]] etc.
[indented] [[italics]] EDGAR BOCHART. [[/italics]]
Gents Mag. for Oct. [[superscript]] r [[/superscript]] 1767. p. 494 & 5. [[/indented]] [[/middle column]]
[[lighter gray ink]] A Nautical Foot is 13,8258 English Inches; this divided into 12 equal parts, each will be a nautical inch. [[/lighter gray ink]]
[[left margin]] The Ratio of a [[underline]] Paris [[/underline]] foot to an [[underline]] English [[/underline]] foot
Gent. Mag. Vol. XIII. p. 142. and also a French Author, say, that "A [[underline]] Paris [[/underline]] toise is equivalent to 76,6 [[underline]] English [[/underline]] inches." ∵ 1,064 ferè [[underline]] English [[/underline]] Inches is a [[underline]] Paris [[/underline]] foot. But in Philos. Trancs. Vol. LXVIII. p.326. it is 76,734. inches Eng. = a Toise. & as 1: 1,06575 ::a Tr.E.: a Tr. Tr. [[/left margin]]
It is generally allowed that a [[underline]] Paris [[/underline]] foot exceeds an english foot by 9 lines. Sir I. N. in his Principia p. 378 l. 31 & 32 [[insertion]] 2nd Edit. Lit III. prop. 19. [[/insertion]] makes 367196 English feet = 57300 Toises; wherefore [[strikethrough]] 367196 [[/strikethrough]] 53700 x 6 feet [[strikethrough]] feet [[/strikethrough]] at [[underline]] Paris [[/underline]]: 367196 feet Eng. :: 1 foot [[underline]] Paris [[/underline]]: 1,068053 ferè, the measure of a [[underline]] Paris [[/underline]] foot in Engl. measure; and 4943,576 [[underline]] Paris [[/underline]] feet [[insertion]] Log. = 3,6940412 [[/insertion]] = 5280 Engl. = 1 mile; But at Page 381.l.9. He says 5000 [[underline]] Paris [[/underline]] feet = one Mile; ∵ 5000:5280::1: 1,056, for a [[underline]] Paris [[/underline]] foot in [[underline]] English [[/underline]] measure; which I do not find used by any other author; but they always make use of 1,068. Which I therefore have follow'd in reducing the following French measures to English miles.
[[left margin]] Measures of
a 1.° on the θ, and its dimentions
thence deduced.
In My Complete Dict. [[superscript]] y [[/superscript]] they make the θ's Polar
Pi diam. = 3931,6 Miles & Equatorial diam. = 397,5. See p.9.
De La Caille, in his Astron. p. 191. Art. 425. makes θ's Semidiam. = 19611500
Paris feet = 3967,068 Engl. Stat. Miles
[[red ink]] N.°3. marked with a red line is from the N. [[superscript]] o [[/superscript]] 4 of of Memoirs of the Royal Academy of Science at Paris, for 1713 by M. Cassini. [[/red ink]]
The Mean of all G... [[/left margin]]
[[table]] [[column 1]]N. [[superscript]] o [[/superscript]]
1.
2.
3.
4.{
5.
6.
[[/column 1]]
[[column 2]]
Name of those who measured
[[underline]] Picard [[/underline]] ----
[[underline]] Norwood []] [/underline]] ----
[[underline]] Cassini [[/underline]] ----
[[bracketed with 4]] Messrs. [[underline]] de Maupertuis [[/underline]], [[strikethrough]] Clairaut [[/strikethrough]] Clairaut, Camus, Le Monier, The Abbé Outhier, & M. Celsius of Uspal [[/bracketed with 4]]
Who corrected [[underline]] Pacard's [[/underline]] N. [[superscript]] os [[/superscript]] ------
De la Caille ---- [[/column 2]]
[[column 3,4,5,6]][[Heading first row]] [[strikethrough]] Places [[/strikethrough]] measured [[/column 3,4,5,6]][[/heading first row]]
[[column 3,4]] [[Heading in second row]] From [[/column 3,4]] [[/heading in second row]]
[[column 3, heading in 3rd row]] Place [[/heading in 3rd ]]row
Amiens
London.
Paris ---
Artic Circle & their middle Lat = 66.° 31N.
Klipfonteyn [[\column 3]]
[[column 4]][[heading]] Latitude [[/heading]]
49..54..46N
51..32N
[[left bracket]] 48 39 N.
48..° 50'.. 10"
Hist. of R. Acad. of Sciences. [[/left bracket]]
Midd. Lat 66..31N
32..41..57 2/3 S. [[/column 4]]
[[column 5,6]][[heading in middle row]] To [[/column 5,6]][[/heading in middle row]]
[[column 5]] [[heading in 3rd row]] Place [[/heading]]
[[superscript]] Malvoisimeor [[/superscript]] Malvicin
York
Colours
Collioure
----
His Observ. [[superscript]] ty [[/superscript]] [[/column 5]]
[[column 6]] [[heading 3rd row]] Latitude [[/heading]]
48..31..48
54..0
42.21
42..31'-13"
Midd. Lat. 66..31N
33.55..15" [[/column 6]
[[column 7]][[heading]] Difference of Latitude [[/heading]]
1 22.5 [[strikethrough]] 5 [[/strikethrough]] 8
2..28..0
6..18.0
6..18..57
1.. . .. .
1..3..17 1/3 [[/column 7]]
[[column 8]] [[heading]] Length of their whole measure. [[/heading]]
78901,3 Toises.
English Feet
905751
360634 Toises & 57100 to a 1°.
57437 Toises
Toises 69669,1 [[/column 8]] [[/table]]
[[table]] [[column 1 heading]] N. [[superscript]] o [[/superscript]] [[/heading]]
1
2
3
4
5
6 [[/column 1]]
[[column 2,3,4,5]] [[1st row heading]] Measure of one deg. on the Merid. deduced from the Observations above [[/column 2,3,4,5 1st row heading]]
[[column 2]] [[heading 2nd row]]Toises [[/heading 2nd row]]
57060
57300
57292
57437
56925
57037
57157 1/6 [[/column 2]]
[[column 3]][[heading 2nd row]] Logarithm. [[/heading 2nd row]]
4,7563318
4,7581546
4,7580940
4,7591917
4,7553030
4,7561567
--------- [[/column 3]]
[[column 4]]
[[heading]]Engl. Miles [[/heading]]
69,25351
69,5448
69,5351
69,71108
69,08966
69,22562
69,39329 ½ [[/column 4]]
[[column 5]] [[heading]] Logarithm [[/heading]]
1,8404419
1,8422647
1,8422041
1,8433018
1,8394131
1,8402668
--------- [[/column 5]]
[[column 6,7]] [[heading 1st row]] Semidiameter of the θ. [[/column 6,7]][[/heading 1st row]]
[[column 6]] [[heading 2nd row]] English Miles. [/heading 2nd row]]
3967,935
3984,624
3984,069
3994,151
3958,547
3966,335
3975,943 ½ [[/column 6]]
[[column 7]] [[heading 2nd row]] Logarithms [[/heading 2nd row]]
3,5985645,3
3,6003873,3
3,6003267,3
3,6014244,3
3,5975357,3
3,5983894,3
-----------[[/column 7]]
[[column 8]] [[heading 1st row]] Circumf. of θ [[/heading in 1st row]]
[[column 8]] [[heading in 2nd row]] in E. Miles. [[/heading in 2nd row]]
24931,27
25036,13
25032,64
25095,98
24872,28
24921,23
24981,59 [[/column 8]] [[/table]]
