The Two Minima Occur, The One From 5 To 7 A.M., The Other From 7 To 8 P.M.; They Are Nearly Equal.
The minima likewise are variable, but only slightly so.
The fifth book contains properties of normals and their envelopes, thus embracing the germs of the theory of evolutes, and also maxima and minima problems, such as to draw the longest and shortest lines from a given point to a conic; the sixth book is concerned with the similarity of conics; the seventh with complementary chords and conjugate diameters; the eighth book, according to the restoration of Edmund Halley, continues the subject of the preceding book.
Buchanan pointed out in 1876, that the great contrasts in surface salinity between the tropical maxima and the equatorial minima give place at the moderate depth of 200 fathoms to a practically uniform salinity in all parts of the ocean.
The maxima and minima in the two phenomena in a good many cases are not found in the same years.
To Zenodorus (c. 200100 B.C.) is due the important problem in maxima and minima that for a given surface the sphere is the solid of maximum volume.
At Cape Thorsden from November to January there seems a distinct double period, with minima near noon and midnight.
Conrad (22) Found Somewhat Similar Results For Q, The Principal Maximum Occurring At I P.M., With Minima At 9 P.M.
Supposing that the two stars are of unequal surface brilliancy, the magnitude at minimum will depend on which of the two stars is the nearer to us, accordingly there are two unequal minima in each revolution.
When the two stars are of equal brilliancy the minima are equal; this is the case in variables of the Geminorum type.