AT THE GREAT PYRAMID DURING THE MONTHS OF JANUARY, FEBRUARY, MARCH, AND APRIL, A.D. 1865; WITH A DISCUSSION OF THE FACTS ASCERTAINED. BY C. PIAZZI SMYTH, F.R. SS. L. & E. F. R.A.S., F.R.S.S.A.; HON. M. INST. ENGIN. SC., P.S. ED., AND R. A. A.S. MUNICH AND PALERMO; |