Schiehallion (2)
I was telling you about the scientific experiment on Schiehallion in
1774. The Astronomer Royal, Nevil Maskelyne, was measuring the mass of
the Earth.
That summer was particularly wet and cold. But, fortunately, there were
nights when the stars were out. Maskelyne measured them with the best
equipment in the world.
He measured the angle to stars from his observatory on the southern
slope of the mountain. Then he did the same thing from another
observatory on the northern slope of the mountain. The two places were
nearly a mile from each other. Maskelyne knew what the difference in
latitude was between the two places. With that, he worked out what
difference there should be in the angle to the same stars between each
observatory.
But the figure he achieved wasn’t equivalent to that. Why? Well, he was
measuring verticality with a pendulum. As he [had] expected, the
mountain was attracting the pendulum a small amount. And, from the
difference between the two numbers, Maskelyne worked out how heavy
Schiehallion was. Then he obtained a figure for the mass of the entire
Earth. And he wasn’t far wrong, according to how people measure the
mass of the Earth today.
Maskelyne found the Gaels very civilized and charitable. He wrote
'their country is with justice celebrated for its hospitality and
attention to strangers’. Among the people he got to know was Duncan Robertson. He was a servant
through the day, carrying loads up and down the mountain. But he was
also an excellent fiddler. In the evening, he was playing reels and
jigs for everyone.
On the final night, there was a knees-up. The bothy went on fire and burned
to the ground. The fiddle disappeared in the fire. Duncan was bereft. And
what happened then? Well, I’ll tell you next week.
Sìth Chailleann (2)
Bha mi ag innse dhuibh mun deuchainn shaidheansail air Sìth Chailleann ann
an seachd ceud deug, seachdad ʼs a ceithir (1774). Bha an Reultair
Rìoghail, Nevil Maskelyne, a tomhas cuideam na cruinne.
Bha an samhradh sin air leth fliuch agus fuar. Ach, gu fortanach, bha
oidhcheannan ann nuair bha na rionnagan a-muigh. Rinn Maskelyne tomhas orra
leis an uidheamachd a b’ fheàrr san t-saoghal.
Rinn e tomhas air a’ cheàrn no angle gu rionnagan bhon
ionad-sheallaidh aige air cliathaich a deas na beinne. An uair sin, rinn e
an aon rud às ionad eile air cliathaich a tuath na beinne. Bha an dà ionad
faisg air mìle air falbh o chèile. Bha fios aig Maskelyne dè an diofar a
bha ann an domhan-leud – no latitude – eadar an dà àite. Le sin,
dh’obraich e a-mach dè an diofar a bu chòir a bhith anns a’ cheàrn do na
h-aon rionnagan eadar gach ionad-seallaidh.
Ach cha robh am figear a fhuair e co-ionann ri sin. Carson? Uill, bha e a’
tomhas dìreachdas le crochadan, no pendulum. Mar a bha e an dùil,
bha a’ bheinn a’ tarraing air a’ chrochadan pìos beag. Agus bhon diofar
eadar an dà àireamh, dh’obraich Maskelyne a-mach dè cho trom ʼs a bha Sìth
Chailleann. An uair sin, fhuair e figear airson cuideam na cruinne gu lèir.
Agus cha robh e fada ceàrr a rèir mar a tha daoine a’ tomhas cuideam na
cruinne an-diugh.
Fhuair Maskelyne na Gàidheil gu math sìobhalta agus carthannach. Sgrìobh e
‘
their country is with justice celebrated for its hospitality and
attention to strangers
’. Am measg nan daoine air an d’ fhuair e eòlas, bha fear Donnchadh
MacDhonnchaidh. Bha e mar sgalag tron latha, a’ giùlan eallachan suas is
sìos a’ bheinn. Ach bha e cuideachd na fhìdhlear air leth. Air an fheasgar
bha e a’ cluich rìdhlichean is sigichean don a h-uile duine.
Air an oidhche mu dheireadh, bha ho-ro-gheallaidh ann. Chaidh am bothan na
smàl agus loisg e gu làr. Dh’fhalbh an fhidheall anns an teine. Bha
Donnchadh troimhe-chèile. Agus dè thachair an uair sin? Uill, innsidh mi
dhuibh an-ath-sheachdain.
