The instrumental settings were made and recorded at the beginning of the analysis of each series of spectra, and when possible were kept untouched throughout the process. The voltage supplying the analyzing beam, and the temperature of the room, were recorded at the beginning and end of each analysis, since both these factors may affect the galvanometer deflection. TABLE II ┌─────────────┬─────────────┬─────────────┬─────────────┬─────────────┐ │Plate Number │ Star │ Slit Width │ Slit Length │ Total │ │ │ │ mm. │ mm. │ Deflection │ │ │ │ │ │ scale div. │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │ MC 20790│ α Lyr │ .25 │ 6.0 │ 77 │ │ 20797│ α Boo │ .10 │ 7.0 │ 35 │ │ 20800│ α Aql │ .10 │ 7.0 │ 42 │ │ 21640│ α Cyg │ .10 │ 5.5 │ 30 │ │ 21645│ δ Cas │ .10 │ 4.0 │ 35 │ │ 21646│ α Cas │ .40 │ 3.0 │ 45 │ │ 21648│ α CMa │ .25 │ 4.0 │ 67 │ │ 21721│ α Aur │ .25 │ 5.0 │ 62 │ │ 21722│ δ CMa │ .25 │ 5.0 │ 74 │ │ 21788│ β Ori │ .25 │ 6.5 │ 91 │ │ 21789│ ε Ori │ .25 │ 6.0 │ 69 │ │ 21802│ α CMa │ .25 │ 6.0 │ 90 │ │ 21803│ α CMa │ .25 │ 6.0 │ 85 │ └─────────────┴─────────────┴─────────────┴─────────────┴─────────────┘ The instrumental settings for the different plates analyzed are summarized in Table II. Successive columns contain the plate number, the name of the star, the width in millimeters of the slit producing the analyzing beam, and the total length of that slit. The effective width of the slit producing the analyzing beam differs somewhat from the quantity recorded in the third column. For the three entries .10, .25 and .40, the corresponding effective slit widths are .101, .262, and .385 mm., respectively. The corresponding widths in millimeters of the analyzing beam are 0.010, 0.026, and 0.038, respectively, which are approximately equivalent to .02, .05, and .08 angstroms at Hδ for the dispersion used in this series of plates.