344 
Scientific Intelligence . 
[Nov. 
In connection with this subject, we may notice a very interesting; paper by M. 
Nicolle, in one of the early volumes of the Journal of Science, N. S. in which 
he attempts to prove that the celebrated and much discussed discrepancy in Me- 
chain’s latitudes of Mont-jouy and Barcelona, was to be explained in a much 
more simple and obvious manner than had yet been attempted. Those of our 
readers who are familiar with the Base du Systems Metrique decimate , are acquainted 
with the history of this question, which, with Zach’s results, has been hitherto 
such a stumbling block to the unqualified admirers of the Cercte Repetiteur. Me- 
chain, the most faithful of observers, as he may be well called, found that his best 
and most unexceptionable results obtained at Mont-jouy and Barcelona, gave a dif- 
ference of latitude 3", 8 more than the actually measured distance (on any pro- 
bable figure and dimensions of the spheroid j gave. The distance on the meri- 
dian was only one mile, so that no solution of the error could be sought for in any 
probable inaccuracy of measurement. Local attraction, and many other causes 
have been assigned, but none of them eveu plausible, excepting Mechain’s own 
explanation, which attributed the error to the instrument, and to the impossibility of 
determining with such small means, quantities so minute. His letters toDelarubre 
on the subject are extremely interesting, and show what a hold the subject had 
taken of his mind, and what a source of mortification and sorrow it became to him. 
M. Nicollet’s paper is exceedingly ingenious. He attempts to show first, that the 
star in the observations of which the greatest discrepancy is observable, £ Urs. Maj. 
is a double star. That the circumstance was not known to, or allowed for by Ma- 
chain, and that being visible in the telescope of the circle, as an ill defined single star, 
the wire was made necessarily to bisect some point between both stars. He al>o brings 
forward other auxiliary considerations connected with the progress of Astronom), 
attempting to show that when the observations are reduced by applying modern 
corrections and the above allowance made, the great discrepancy of 3 8 is entirely 
got rid of. It would be impossible to do justice to his paper in the limits we are 
confined to ; it is, as we before remarked, exceedingly clever and ingenious. Unfortu- 
nately however, for the success of the opinions it promulgates, we ha ve in the March 
number of the Philosophical Magazine, a letter from a French correspondent, who 
at once demolishes M. Nicollet’s carefully reared fabric, lfe shows from Mechain’s 
own letters, that he not only knew the star £ Vrs. Maj. to be double, but saw it so 
in the telescope of his circle, and describes the lesser star to be, when he brought 
the wire on the centre of the large one , about two diameters of the wire below or 
about 12'' And the other arguments he summarily disposes of by taking the same 
stars , observed at the same season of the year at both places, (though in different 
years,) in which case, all doubt as to the coefficients of the different corrections 
must vanish. As a useful memorandum, we shall here give the result of his com- 
parison. 
The difference of Latitude by a Polaris, 
Sup, 
Pass. 
61," 19 
Do.' 
Inf. 
Pass. 
59,44 
(i Urs. min. .. 
Sup. 
Pass. 
62,65 
Ditto 
Inf. 
Pass. 
63,16 
£ Urs. maj. . . 
Sup. 
Pass. 
58,10 
Ditto 
Inf. 
Pass. 
64,88 
Gem. .. 
57,83 
By measurement it was found to be 
59,33 
These results prove, that no latitude deduced from observations made with this 
instrument can be depended on to so small a quantity, as the admirers of the instru- 
ment would have us believe. — And they lessen the force of the objections made 
to the regular figure of the earth, founded, partly on similar discrepancies in arcs 
of greater extent. The English irregularities have, as far as we recollect, been 
plausibly referred to local attractions acting on the plummet. 
2. New System of Water Power - 
A description with plans of a mode of supplying public works with water as a 
moving power in all situations, and at all seasons ot the year, has been lately pub- 
lished in Scotland by au engineer of the name of Thom. It promises to be of 
the greatest advantage to this country, not only as affording a cheap substitute for 
steam power, but as lending a powerful aid to the amelioration of the condition of 
the working classes, and perhaps of becoming the means of removing the intolerable 
nuisance ot smoke in large towns. This plan of water-power, which has been adopted 
at Greenock on a beautiful water-fall of 512 ft. height above the level of the sea, is 
capable of universal application throughout the island, and is rendered complete by 
