92 



rOPULAR SCIENCE NEWS. 



[June, 1888. 



halfway up, and Scorpius, with Jupiter, is a little 

 below and to the east of Libra; Sagittarius is on 

 the south-east horizon ; Corona Borealis is near the 

 zenith, to the south-east; Hercules is high up in 

 the east, and Aquila is below it; Lyra is about half- 

 way from horizon to zenith, a little north of east; 

 and Cygnus is below Lyra, in the north-east. The 

 bright stars in the head of Draco are in the north- 

 east, high up. Ursa Minor is on the meridian, 

 mainly between the pole and the zenith; Cepheus is 

 a little below and to the right of the pole star, and 

 Cassiopeia is near the horizon, a little east of north ; 

 Auriga is just setting about 20° west of the north 

 point; Ursa Major is in the north-west, high up; 

 Gemini is setting a little north of west; Cancer, 

 with Saturn, is a little above, to the left; Leo is 

 above Cancer, and nearly due west; Virgo, with 

 Mars and Uranus, is in the south-west, about half- 

 way up. 



Princeton, May 5, 1888. 



[Specially reported for the Popular Science News.'] 

 METEOROLOGY FOR APRIL, 1888. 



TEMPERATURE. 



The 8th was the coldest, and the 28th the warm- 

 est, day of the month, averaging 28^° and 62° 

 respectively. The 29th was only one-third of a 

 degree below the 28th. The lowest point reached 

 was 22°, on the 8th; the highest 77°, on the 28th. 

 The entire month was 1.80° below the average of 

 April in eighteen years. The second average was 

 42.29°. The temperature was very uniform on the 

 2d, varying only from 36° to 39°. The most sud- 

 den change was 21° in seventeen hours, following 

 2 P.M. on the 7th. 



SKY. 



The face of the sky in 90 observations gave 55 

 fair, 7 cloudy, 20 overcast, 6 rainy, and 2 snowy, 



— a percentage of .611 fair. The avei-age fair 

 observations the last eighteen Aprils has been 514, 

 with extremes of .322, in 1878, and .700, in 1872. 

 Thunder and lightning occurred about 3 a.m. on 

 the 6th. 



PRECIPITATION. 



The amount of precipitation the past month, 

 including snow, was 3.02 inches, while the aver- 

 age for the last twenty Aprils has been 3.94, with 

 extremes of 1.20, in 1869, and 8.50, in 1870. 

 There were traces of snow on the 2d and 21st, 

 with half an inch on the 10th. From this last 

 date to the end of the month the precipitation 

 was only .32 inch. As illustrative of the beautiful 

 variety in nature, may be mentioned the slight 

 trace of snow on the afternoon of the 21st, which 

 fell, not as feathery flakes, but in tiny, solid spheres, 

 as if fairies were indulging in a merry game of 

 snowball. 



PRE88URE. 



The average pressure was 30.054 inches, with 

 extremesof 29.65, on the 2d, and 30.47, on the 26th, 



— a range of .82 inch. The average for the last 

 fifteen Aprils has been 29.891, with extremes of 

 29.767, in 1884, and 30.078, in 1886. The sum 

 of the daily variations was 5 32 inches, giving an 

 average daily movement of .177 inch, which is the 

 average for the last fifteen Aprils, with extremes 



of .139 and .239. The largest daily movements 

 were .48 inch, on the 3d, .40, on the 2d, and .38, 

 on the 6th, all in connection with rainfall. The 

 barometric pressure was remarkably high for April, 

 exceeded but once in fifteen years ; and the changes 

 slight but frequent. A high pressure seems to 

 check precipitation. 



WINDS. 



The direction of the wind in 90 observations 

 gave 15 N., 3 S., 6 E., 16 W., 3 N.E., 33 N.W., 

 5 S.E., and 9 S.W., an excess of 34 northerly and 

 44 westerly over the southerly and easterly, indi- 

 cating the approximate average direction to be 

 W. 37° 42' N. The westerly winds in April for 

 nineteen years have uniformly prevailed over the 

 easterly, with two exceptions (1870 and 1877), by 

 an average of 25.42 observations, and the north- 

 erly over the southerly, with a single exception 

 (1880), by an average of 21.37; showing the 

 general average of April in nineteen years to be 

 W. 40° 3' N. The relative progressive distance 

 travelled by the wind the past month was 55.61 

 units, and during the last nineteen Aprils 631 

 such units, — an average of 33.21 ; showing far less 

 opposing winds than usual. 



IN REVIEW. 



The present April has been unusually cold and 

 fair, with high pressure, and winds largely north- 

 westerly. Their unit distance travelled was also 

 unusually large, and the rainfall small, for April. 



D. W. 

 Natick, May 7, 1888. 



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 he published. 



Questions regarding the treatment of diseases can- 

 not be answered in this column. 



C. W. — (1) Storage batteries do not really store elec- 

 tricity, but are simply batteries which, after having 

 once produced a current of electricity by chemicals in 

 the ordinary way, can be renewed by passing anotlier 

 current througli them in a reverse direction. They can 

 then produce another direct current as before. (2) Cel- 

 luloid is principally composed of gun-cotton and cam- 

 phor. We know of no reason why celluloid collars or 

 cuffs should produce eruptions on the skin, or be inju- 

 rious in any way. (.3) Galvanized iron vessels should 

 not be used in the dairy, as the zinc is readily attacked 

 by the acid of sour milk (lactic acid), forming un- 

 wholesome salts. 



E. W. A., Texas.— A. "dialytic" telescope is one 

 containing an additional lens, about halfway between 

 the object-glass and eyepiece, for the purpose of cor- 

 recting those errors of refraction which produce chro- 

 matic "aberration, or colored fringes around the objects 

 viewed. This arrangement is now very rarely met 

 with, as the usual plan is to make the object-gla.ss 

 itself of two pieces of glass of different densities, by 

 which the aberration is entirely prevented. 



A. T, New York. — How are the lest-papers pre- 

 pared for detecting the presence of ozone in the 

 atmosphere? 



Aiiswer. — A thin paste is made with boiling water 

 and starch, a few drops of solution of iodide of potas- 

 sium added, and the mixture well stirred with a glass 

 rod. This is brushed over strips of white filter or 

 blotting paper, which are exposed to the air while 

 damp. If ozone is present, the iodide of potassium is 

 decomposed, and the iodine unites with the starch, 

 forming a blue compound. These papers must be 

 freshly made each time tliey are used, and not allowed 

 to dry. 



O. W. D., Massachusetls. — Does mica transmit the 

 rays of light and heat with equal freedom V 



Answer. — Ix, depends upon the color of the mica. 

 The white, transparent varieties transmit a larger pro- 

 portion of light rays, while the dark-colored micas may 

 be nearly o])aque to light, and yet transmit nearly as 

 much heat as the transparent mineral. We do not 

 find the relative diathermancy of mica given by any 

 authority to which we can refer. 



J. A. M., Texas. — Is the length of the day and night 

 equal at all points on the equator, or only where it is 

 intersected by the ecliptic? 



Answer. — Without taking into account the small 

 variations due to refraction, etc., the days and nights 

 are always of equal length at all points on the equator, 

 without regard to the position of the ecliptic. 



E. B. S., Virginia. — What is meant by gold being so 

 many " carats fine " ? 



Answer. — A "carat" is a weight used by jewellers, 

 and is equal to twelve grains. The weight is used 

 arbitrarily to denote tlie proportion of pure gold in an 

 alloy. Twenty-four carats fine is pure gold; eighteen 

 carats fine, eighteen parts of gold, and si.'c of copper or 

 silver. Nearly all gold coins and jewelry are alloyed 

 with copper or silver, to make the metal harder and 

 more durable. 



S. L., Belmont. — What is the cause of the phospho- 

 rescent light produced by glow-worms and similar 

 insects? 



Answer. — Recent investigations seem to show that 

 it is caused by a substance called noctilucine, which is 

 secreted by the animal, and that the light is due to the 

 slow oxidation of that substance. If some of these 

 insects have been seen to retain their luminosity in a 

 vacuum or in hydrogen gas, it is because their tissue 

 always contains enough oxygen to allow the slow 

 oxidation of the noctilucine to continue under the cir- 

 cumstances for a certain length of time. 



LITERARY NOTES. 



Volcanoes and Earthquakes. By Samuel Kneeland, 

 A.M., M.D. Boston: D.Lothrop& Co. $2.50. 

 This handsome volume gives " a popular account 

 of the nature, causes, effects, and geographical distri- 

 bution of volcanoes and earthquakes, from personal 

 observation in the Hawaiian and Pliilipinne Islands, 

 Japan, Iceland, the Mediterranean Basin, Spain, and 

 the United States." The fact that the material is the 

 result of the author's own observation adds to the 

 interest of the book, no less than to its accuracy. It 

 reads like a history of personal adventure, rather than 

 like a dry, scientific treatise, and thus becomes " pop- 

 ular" in the best sense, while it is thoroughly scien- 

 tific. The illustrations are coarse ; but, being from 

 photographs and drawings made on the spot, they are 

 true to nature, and serve to make many points clear 

 which words coulil not adequately describe. 



The Satchel Gnide to Enrope. ,3d edition for 1888. 



Boston: Houghton, Mifflin, & Co. S1.50. 



This useful companion for the vacation tourist in- 

 creases in popularity every year. Five editions were 

 issued in 1887, and the third for 1888 has already been 

 called for. The success of the book is due to its hon- 

 esty and accuracy, and to the fact that it hits the golden 

 mean between the extreme conciseness of guide-Viooks 

 which, in attempting to put all Europe intoa", pocket " 

 form, give merely a dry, index-like list of objects of 

 interest, and the bulky diffuseness of volumes which, 

 though good reading at home before or after a tour, 

 are clumsy and inconvenient while travelling, espe- 

 cially if one takes the minimum of luggage. 



Principles and Practice of Morality. By Ezekiel,GiIman 

 Robinson, D.D , LL.D , President of Brown Uni- 

 versity. Introductory price, $1.50. Silver, Rogers, 

 & Co., publishers, .10 Bromfield Street, Boston. 

 The whole subject of morals has been exhaustively 

 rediscussed in recent years, from both the scientific 

 and the philosophical points of view. The results of 

 the rediscussion are seen in a marked modification of 

 ethical theories. The basis of utilitarianism has been 

 reconstructed, and corresponding changes have taken 

 place in the methods of intuitipnisni. 



As a text-book on this important subject. President 

 Robinson's Principles and Practice of Morality can- 

 not fail to attract wide attention, and to command the 

 interest of all teachers, students, and general readers 

 of ethical science. It is a timely book, such as might 

 be expected from its eminent and learned author, and 

 we predict for it extensive use in the colleges of the 

 country. 



— • — 



The Writers' Publishing Company of New York 

 have issued a handbook of the Agassiz Association, 

 under the title Tliree Kinndoms. It is especially de- 

 voted to the purposes of this most useful society, and 

 gives a great deal of valuable information regarding 

 the collection and preservation of natural objects and 

 curiosities, whether animal, vegetable, or mineral. 



The Three Ethical Codes. By the Illustrated Medical 

 Journal Company, publishers, Detroit, Mich. Cloth, 

 55 pages. Postpaid, 50 cents. 

 It IS a handy little book for reference as occasions 



may require. 



