554 BEPOET — 1886. 



a system of sweeping, with a direct-vision prism attached to the eyepiece of the 

 equatorial telescope, resulted in the discovery by the present writer of several 

 additional objects of the same class. Still more recently Dr. Copeland, during a 

 journey to the Andes, has extended the list by the discovery of some similar stars 

 in the southern heavens. 



Among the photographic observations which have been undertaken at Harvard- 

 College Observatory, as a memorial to the late Professor Henry Draper, is included 

 a series of photographs of the spectra of all moderately bright stars visible in 

 the latitude of the observatory. A recent photograph of the region in Cygnus 

 previously known to contain four spectra exhibiting bright lines has served to 

 bring to our knowledge four other spectra of the same Innd. One of these is that 

 of the comparatively bright star P. Cygni, in which bright lines, apparently due to 

 hydrogen, are distinctly visible. This phenomenon recalls the circumstances of 

 the outburst of light in the star T. Coronae, especially when the former history of 

 P. Cygni is considered. According to Schonfeld it first attracted attention as an 

 apparently new star in 1600, and fluctuated greatly during the seventeenth 

 century, finally becoming a star of the fifth magnitude, and so continuing to the 

 present time. It has recently been repeatedly observed at Harvard CoUege Ob- 

 servatory with the meridian photometer, and does not appear to be undergoing 

 any variation at present. 



Another of the stars shown by the photograph to have bright lines is D.M. + 37° 

 3821, where the lines are unmistakably evident, and can readilj' be seen by direct 

 observation vnth the prism. The star has been overlooked, however, in several 

 previous examinations of the region, which illustrates the value of photography in 

 the detection of objects of this kind. 



The other two stars first shown by the photograph to have spectra containing 

 bright lines are relatively inconspicuous. The following list contains the desig- 

 nations, according to the Durchmusterung, of all eight stars, the first four being 

 those previously known: 35° 4001, 3.5° 4013, 36° .3956, 36° 3987, 37° 3821,. 

 38° 4010, 37° 3871, 35° 3952 or 3963. Of these 37° 3871 is P. Cygiii, and 

 37° 3821 is the star in the spectrum of which the bright lines are most distinct. 



4, An Apparatus for determwiing the Hardness of Metals. 

 By Thomas Turner, A.B.S.M. 



Hitherto there have been but few attempts to quantitatively determine the 

 relative hardness of metals. The method adopted by the United States Govern- 

 ment in 1856 consisted in the punching of a hole by a tool in the form of a 

 pyramid and under a constant pressure. The indentation was carefully measured, 

 its capacity calculated, and in this way relative hardness was expressed. But it 

 has been shown that the results obtained reaUy depended in part upon tenacity, 

 and so were not accurate representations of hardness. In 1859 Calvert and John- 

 son employed a modification of the same methodj which was further improved by 

 Bottone in 1873. 



The apparatus recommended by the author is an adoption of the method which 

 has already been employed in determinations of the hardness of minerals, namely, 

 by scratching the surface with a weighted diamond. The diamond is attached to 

 a graduated beam arranged so as to allow of motion in both a horizontal and a 

 vertical plane. By means of a sliding weight, sufficient pressure is applied to cause 

 a distinct scratch on drawing the diamond over a smooth surface of the metal to 

 be tested. The weight is then moved until the diamond just ceases to produce a 

 visible scratch, when the position of the weight on the scale is observed. Some 

 experience is necessary in observing the scratch, but when this has been obtained 

 the apparatus gives uniform results. 



The author's experiments with cast iron have shown fhe common idea that 

 hardness and tenacity necessarily accompany each other to be erroneous. Very soft 

 cast iron can be obtained with a high tensile strength, while hard cast-iron has 

 very often a low tensile strength. A\Tien metal has to be worked, unnecessary 



