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Nothing has afforded me so convincing a proof of the unity of the Deity as these purely mental conceptions of numerical and mathematical science which have been by slow degrees vouchsafed to man, and are still granted in these latter times by the Differential Calculus, now superseded by the Higher Algebra, all of which must have existed in that sublimely omniscient Mind from eternity.
Martha Somerville (ed.), Personal Recollections of Mary Somerville, Boston, 1874.
Giuseppe Alberti's Instruzioni pratiche per lingenero civile
Plate VII from Giuseppe Alberti’s Instruzioni pratiche per l’ingenero civile, (1774) [Practical Instructions for Civil Engineers]. Alberti (1712 - 1768) was an Italian engineer and architect. This illustration on page 298 explains the triangulation method of land measurement employing a sighting staff or surveyor’s cross. The instrument shown contains a compass for marking bearings.