the ‘Trigonometrical Operation. 253 
were detained a whole week, before the white lights, notwith- 
standing their extraordinary brilliancy, could be feen at Han- 
ger-hill Tower, or even at Argyll Street, the north -eat wind, 
which then prevailed, having brought the impenetrable mafs 
of frrioke between the ftation of theindrument and the points 
to be obferved ; and at lad we were obliged to watch all night, 
till tow aids tne morning the fires of L.ondon hemp* extin— 
guifhed, the white lights could then be interfered. 
It is not therefore furprifing, that from the Nations of Nor- 
wood, Greenwich, and Shooter’s Hill, we fhould only be able 
to fix, in a fatisfadory manner, two points in London, namely, 
St. Paul’s and Argyll Street. Bearings, it is true, of others 
were taken ; but that thefe might be interfered by angles not 
too acute, it became neceflary to make ufe of obfervations that 
had been formerly obtained at Argyll Street with my own 
infirument in its vertical pofxtion, and at St. Paul’s with the 
adronomical quadrant. Moreover, by way of finifhing the 
operation, and fumifhing fuch part of the inhabitants of the 
metropolis as may be curious in matters of this fort with a fet 
of didances that cannot fail to be ufeful to them, two new 
dations were chofen for the great infirument to the northward 
of London, one on Hot nj'ey L/j//, and the other on Primroje 
Uni. Thus, from the combined operations at thefe feveral 
places, we have been able to determine the fituation of thirty - 
feven confpicuous points, confiding chiefly of the mod re- 
markable deeples in and near the capital. 
By referring to Plate XI. which is in fad the fkeleton, but on 
a very fmall fcale, for an improved plan of London and its 
environs, the relative fituation of thefe points with regard to 
St. Paul s, and the four neared dations of the great feries, 
will be feen. Some of the principal of thefe fecondary tri- 
3 ... angles 
