Just look over the list--mechanical drawing and mechanical processes, analytical geometry, calculus, physics, chemistry, English literature, French and Spanish, integral calculus, spherical trigonometry, stereographic projection and United States Naval history!
Their calculations on the eccentricity of the moon prove that they had a rectilinear trigonometry and tables of chords.
Fusion mathematics; a correlation and unification of intermediate algebra & plane trigonometry.
Here are two other entries in the Diary:-- Aug. 26th.--Worked from about 9.45 to 6.45, and again from 10.15 to 11.45 (making 101/2 hours altogether) at an idea which occurred to me of finding limits for pi by elementary trigonometry, for the benefit of the circle-squarers.