ON THE MANUFACTURE AND DURAB1L21 i OF ROOFING-SLATE. 569 
SUN AND PLANETS FOR JANUARY, 1884. 
W. DAWSON, SPICELAND, IND. 
On January ist it has been ten days since the Sun passed Winter Solstice, 
where his R. A. was 18 hours. Increasing in R. A. at the rate of about four 
minutes a day, brings him on the ist of January at noon to i8h. 47m.; and hav- 
ing declined northward nearly half a degree, makes his declination 23° i' S. He 
runs northward 5^° during the month, being in south declination 17° 24' on the 
31st; and R. A. 2oh. 55m., on the last noon of the month. On the ist. Sun is 
slow of M. T. by 3m. 44s. So, when he is on the meridian (exactly south) it is 
i2h. 3m. 45s. by mean or clock time, which is the right time to use in the com- 
mon affairs of life. The le^i st number of sun-spots observed during the past 
month is 12, on December 5th; the greatest number is 120, on December 12th. 
Mercury is Evening Star till January 20th. It will be farthest east and best 
seen on the 4th, being then about half an hour below Venus, which is very 
bright. Both planets set a little north of where the Sun does. Mars rises on 
January ist about 8 o'clock in the evening; and at 5 o'clock on the 31st. This 
planet retrogrades — goes backward, or east, among the stars — from R. A. ph. 
40. to ph. 4m. during January. It is a few degrees northwesterly from Regulus, 
in Leo. Jupiter rises soon after 6 P. M. in the fore part of the month, and will 
be splendid for observation all winter. He will be in opposition to the Sun Jan- 
uary 19th. Jupiter and Saturn are also retrograding very slowly. Saturn rises 
soon after 2 P. M. on the ist, and of course, is three or four hours high at dark. 
It still holds its place a few degrees above and to the left of Aldebaran in Taurus. 
This is a worthy object for the telescope. The Moon will pass through between 
it and Aldebaran soon after midnight January 8th. Uranus is now in Virgo, 
nearly between the stars Beta and Eta of this constellation. Neptune is on the 
confines of Aries and Taurus, about 10° southwest of the Pleiades. 
ARTS AND MANUFACTURES. 
ON THE MANUFACTURE AND DURABILITY OF ROOFING-SLATE. 
E. H. S. BAILEY, PH.D. 
Slates suitable for working are found associated with many metamorphic 
rocks, especially those of the Silurian period. They are closely related to mica- 
ceous rocks and often graduate into them. That the lamination or slaty cleavage 
was produced by lateral pressure, and that, not at the time of bedding of the 
