1S8 
POPULAR SCIEITCE WEWS. 
[September, 1891. 
[Specially ObBerved for Populak Science News.] 
METEOROLOGY FOR JULY, 1891. 
TEMPERATURE. 
Average Thermometer. 
Lowest. 
Highest. 
Kange. 
At7A. M 
At2P. M 
At9P. M 
Whole month .... 
Second average . . . 
64.45° 
75.58° 
64.97° 
68.33° 
67.49° 
56° 
68° 
68° 
56° 
56° 
74° 
87° 
74° 
87° 
87° 
18° 
19° 
16° 
31° 
31° 
l.a8t21JulyB .... 
Second average . . . 
71.16° 
70.39° 
68.33° 
In 1891. 
67.49° 
74.80° ) 
in 1887. S 
73.88° 
6.47° 
6.39° 
The present July hag been the coolest in twenty- 
one years. The lowest point was 56°, on the 28th ; 
the highest, 87°, on the 13th. The 3l8t was the 
coolest day, with an average of 62.66° ; the 14th 
was the warmest, at 77°, — a range of only 14.33°. 
The mercury reached 80° or above only six times 
during the month, at the hours of observation, 
and the entire month was 2.83° below the average 
of the last twenty-one Julys. The seven months 
since January 1 have been 1.47° daily above the 
average of this period, giving a surplus of heat 
thus far in the year of 312°. This surplus, how- 
ever, came during the first four colder months, 
while our chief loss came in July, leaving the bal- 
ance as above. 
SKY. 
The face of the sky, in 93 observations, gave 48 
fair, 15 cloudy, 21 overcast, and 9 r.ainy, — a per- 
centage of 51.6 fair, the same as last year. The 
average fair for the last twenty-one Julys has 
been 60.3, with extremes of 41.9 in 1889, and 76.3 
in 1878. Only four Julys have been less fair than 
the present during my record. Thunder and 
lightning occurred on the 3d and 25th, the latter 
in the south, but without rain in this locality. 
PRECIPITATION. 
The amount of rainfall the last month was 2.93 
inches, chiefly toward the close of the month; 
only .13 inch fell between the 8th and 23d. The 
four princip.al rains ranged from .55 to .77 inch 
each, keeping vegetation generally in a flourishing 
condition. The average amount the last twenty- 
three Julys has been 3.20 inches, with extremes 
of 1.20 in 1888, and 9.27 in 1889. The amount 
since January 1 has been 35.76 inches, and the 
average of these seven months the last twenty- 
three years only 28.25 inches, — giving a surplus 
this year thus far of 7.51 inches. 
PRESSURE. 
The average pressure the past month vvas 29.994 
inches, with extremes of 29.70 on the 8th, and 
30.30 on the 23d, — a range of .60 inch. The mean 
for the last eighteen Julys has been 29.933 inches, 
with extremes of 29.820 in 1884, and -29.994 in 
1891, — a range of .174 inch. The mean daily 
movement was .099 inch. This average tlie last 
eighteen Julys has been .092, with extremes of 
of .074 and .118. The largest daily movements 
were .34 inch on the 8th and 24th, and .20 on the 
30th, — showing a quiet state of the atmosphere, 
as is usual in the warmest months. Eighteen ob- 
servations of the 62 were recorded stationary. 
WINDS. 
The average direction of the wind the past 
month was W. 37° 53' S., while the mean for the 
last twenty-two Julys has been W. 25° 3' S., with 
extremes of W. 4° 54' N. in 1889, and W. 66° 15' S. 
in 1873, — a range of 71° 9', or nearly six and one- 
quarter points of the compass. The relative pro- 
gressive distance travelled the last month was 
57.01 units, and during the last twenty-two Julys 
1,065 such units, an average of 48.41, — showing 
less easterly winds than usual. ITie northerly 
winds have prevailed over the southerly in July 
only twice in twenty-two years, and these but 
very slightly. 
In review, the past month has been remarkably 
cool, with high pressure, more clouds and more 
northerly winds than usual in July, with slightly 
less rainfall than the average ; but since January 
1 both heat and precipitation — the two items most 
essential to vegetation — have been quite in excess. 
D. W. 
Natick, August 5, 1891. 
[Specially Computed for Popular Science News.] 
ASTRONOMICAL PHENOMENA FOR 
SEPTEMBER, 1891. 
The sun crosses the equator and autumn begins 
September 23, at 3 A. M. The planets are not in 
very good position for observation, Jupiter being 
about the only one easily seen. Mercury at the 
beginning of the month is an evening star, about 
17° east and south of the sun— too far south to be 
easily seen after sunset. It passes inferior con- 
junction at midnight on September 12, and be- 
comes a morning star. It reaches greatest west- 
ern elongation on September 28, rising then about 
an hour before sunrise — not quite far enough 
away to be easily seen. Venus is also not in 
good position, being quite near the sun during the 
whole month. It passes superior conjunction on 
the morning of September 18, changing from a 
morning to an evening star, but will probably be 
out of sight during the whole month. Mars is a 
morning star, rising about an hour and a half 
before the sun at the end of the month, but it is 
too faint to be conspicuous. It is in aphelion at 
midnight on September 29. Jupiter is in good 
position. It rises about sunset at the beginning 
of the month, and is in opposition with the sun on 
September 5, at 5 P. M. It is in the constellation 
Aquarius, and during the month moves about 4° 
east and south. The following eclipses of his 
satellites may be seen during the month. Before 
opposition on September 5 the phenomena are all 
disappearances, and take place just off the left- 
hand limb of the planet, as seen in an inverting 
telescope. After opposition the shadow of the 
planet is on the right-hand side, and the disap- 
pearances are no longer seen, but the phenomena 
are all reappearances seen off the right-hand limb. 
Times are Eastern Standard. 
II. D. September 
1. D. September 
II. R. September 
III. R. September 
IV. R. September 
I. R. September 
II. R. September 
III. R. .September 
I. R. September 
I. R. September 
II. R. September 
I. R. September 
I. R. September 
II. R. September 
IV. R. September 
I. R. September 
3, 7h. Om. A. M. 
4, 2h. 32m. A. M. 
6, lib. 3m. P. M. 
7, 4h. 18m. A. M. 
12, 12h. 39m. A. M. 
13, Ih. 10m. A. M. 
14, Ih. 39m. A. M. 
14, 8h. 19m. A. M. 
14, 7h. .39m. P. M. 
20, 3h. 5m. A. M. 
21, 4h. 14m. A. M. 
21, 9h. .34ra. P. M. 
27, 5h. Onf. A. M. 
28, 6h. 50m. A. M. 
28, 6h. 49m. P. M. 
28, llh. 29m. P. M. 
Saturn changes from an evening to a morning 
star, passing conjunction with the sun on the 
morning of September 13. It is too near the sun 
throughout the month to be conspicuous. The 
rings disappear on September 22, owing to the 
earth passing through the plane of the rings. 
They will reappear again on October 30, when the 
sun passes through the plane. Uranus is still an 
evening star in the constellation Virgo, but sets 
not long after the sun. Neptune is a morning 
star in the constellation Taurus, near the group 
of the Hyades. It is in quadrature with the sun 
on the morning of September 1. 
TTie Constellations. — The positions given hold 
good for latitudes differing not many degrees 
from 40° north, and for 10 P. M. on September 1, 
9 P. M. on September 15, and 8 P. M. on Septem- 
ber 30. Cygnus is directly overhead. Delphinus, 
high up, and Capricornus, low down, are on the 
southern meridian. Piscis Australis is below 
Capricornus, and not quite up to the meridian. 
Aquarius is to the left of Capricornus, at about 
the same altitude. After Aquarius come Pisces 
and Aries, the latter being almost due east, at 
about 10° altitude. Taurus is just rising, a little 
north of east. Pegasus is between Pisces and the 
zenith; and Andromeda is above and a little to 
the north of Aries. Cassiopeia is to the right and 
a little above the pole star. Perseus is low down 
in the northeast, and Auriga is just rising below 
it. Draco is to the west of the meridian. Ursa 
Minor is mainly to the west of the pole star, at 
about the same altitude. Ursa Major is below the 
pole, a little to the left. Lyra is just to the west 
of the zenith, with Hercules, Corona Borealis, and 
Bootes below it, the last being near the horizon, a 
little north of west. Scorpius is setting in the 
southwest, with Ophiuchus above it. Sagittarius 
is low down in the south, a little west of the me- 
ridian ; and Aquila is high up, between Sagitta- 
rius and Cygnus. M. 
Lake Forest, III., August 1, 1891. 
»♦+ ■ 
QUESTIONS AND ANSWERS. 
Letters of inquiry should enclose a two-cent 
stamp, as well as the name and address of the 
writer, which will not be published. 
Questions regarding the treatment of diseases 
cannot be answered in this column. 
P. E. O., St. Louis. — Wliat is the strongest or 
most tenacious metal when in the form of wire ? 
Answer. — Cast steel wire is the strongest, a wire 
with a sectional area of one square millimeter sus- 
taining a weight of about 184 pounds. Antimony 
is the weakest metal, breaking with a weight of 
one and a half pounds. Other metals give the 
following figures under the same conditions : 
Lead, 5.19 pounds; gold, 61.60; pUatfiium, 77; 
copper, 90.20; and iron, 140.71. 
W. M. M., Illinois. — Is permanganate of potash 
a safe and reliable agent for purifying foul water 
in a cistern ? 
Answer. — Permanganate of potash is a powerful 
oxidizing agent, and under favorable circum- 
stances will destroy organic matter, but it is by 
no means suited for the purification of water. 
This cannot be satisfactorily accomplished by 
any chemical, and we should advise you to throw 
all the water in the cistern away, give it a 
thorough cleansing, and allow it to fill up again. 
If it is absolutely necessary to use the water, it 
shoulii first be boiled for about an hour, and then 
filtered through flannel ; but it is a very diflicult 
matter to purify water that has once become pol- 
luted. 
A. W. B., Boston. — IIow can I raise the boiling- 
point of water under the usual atmospheric pres- 
sure? 
Answer. — By dissolving common salt in water 
to saturation, it may be made to boil at 219° F. 
Saturated solutions of nitrate of potassium boil at 
240°, carbonate of potassium at 275°, and chloride 
of calcium at 354°. Care must be taken in apply- 
ing heat to these heavy solutions, as they are 
likely to "bump,"' or suddenly burst into ebulli- 
tion with explosive violence. 
Subscriber.— What is the velocity of light? 
Answer. — As determined by Foucault, it is 185,- 
157 miles a second. This determination is un- 
doubtedly very nearly exact, although the me- 
chanical difficulties in the way of measuring such 
an immense velocity render it difficult to obtain 
perfectly accurate figures. 
