Feb. 3, 1888.] 



SCIENTIFIC NEWS. 



113 



recommended by the author are in common use among 

 physicians, but we must remind our readers, lest they 

 hasten in search of a cheap substitute for the family 

 doctor, that it is one thing to take pills and quite another 

 thing to make the diagnosis which converts those pills 

 from dangerous weapons into useful remedies. 



Tounial of the Society of Telegraph Engineers and Electri- 

 cians. Vol. xvi.. No. 68. (London and New York: 

 E. and F. N. Spon.) 

 Perhaps the most generally interesting paper in this 

 issue is that of " Deep-Sea Soundings in connection with 

 Submarine Telegraphy," by Mr. E. Stallibrass. The 

 author points out how little precise information we even 

 yet possess concerning the bed of the ocean. Captain 

 Maury's notion of the bed of the sea between Ireland and 

 Newfoundland being a plateau, which seems to have 

 been placed there expressly for the purpose of holding 

 the wires of a submarine telegraph, can now no longer 

 be maintained. 



Institution of Mechanical Engineers. Proceedings, August, 

 1887, Edinburgh Meeting. 



The papers read at this congress are of too purely 

 technical a nature to admit of discussion in our pages. 

 There is an account of the electric light on the Isle 

 of May, by Mr. D. A. Stevenson, F.R.S.E. It 

 appears that on account of the large first cost and 

 yearly maintenance, the Trinity House have resolved to 

 adopt the electric light in the most important positions 

 only, and this decision the author regards as judicious. 

 The May Island lights are probably the most powerful 

 existing in the world. 



Professor Sir William Thomson, F.R.S., delivered an 

 important lecture on " Ship Waves," which he intro- 

 duced by an interesting account of waves in general. He 

 mentioned that in light-waves the vibrations occur per- 

 pendicularly to the line of progression of the wave. 

 In sound-waves, on the contrary, the vibration is along 

 the line of propagation of the wave. Waves of 

 water agree more nearly with light-waves than with 

 sound-waves. 



_ •-J»ta^<^*<f-» ■ 



LEAP-YEAR. 



ACCORDING to the original Roman calendar, the 

 civil year began with March, and was divided into 

 ten months, consisting of an unequal number of days, in 

 all 304 days. It was, however, soon discovered that on 

 the same day in successive years there was a considerable 

 difference in the number of hours during which the sun 

 was above the horizon. Accordingly two months were 

 added to the year. Numa, in imitation of the Greeks, 

 divided the year into twelve months, according to the 

 course of the moon, of 30 and 29 days alternately, making 

 354 days, and as an even number appeared of bad 

 portent, he added a day, making the year consist of 355 

 days. 



But this lunar year was seen to be too short in com- 

 parison with the solar year, to the extent of about ten 

 days. Accordingly Numa intercalated every other year 

 an extraordinary month of 22 and 23 days alternately. 

 It was, however, left to Julius Cassar, great in calculation 

 as well as in war, to grasp the difficulty with a practical 

 hand. He got the celebrated astronomer, Sosigenes, of 

 Alexandria, to adjust the error. That was in the year 

 47 B.C. — the last year of confusion — which contained 



fifteen months or 445 days. Everything then proceeded 

 pretty regularly from the first of January. The solar 

 year having been found to consist of 365I days, Julius 

 Caesar enacted that every fourth year should consist of 

 366 days. This was called the "leap-year," or bissextile 

 year, when February had 29 days. With the assistance 

 of Flavius, he assigned to the months the number of days 

 which they still retain. After his great name that year con- 

 tinued for sixteen centuries to be called the "Julian year" 

 all over intelligent Europe, and Russia to this day. In 

 Christian countries it has been, with a modification, the 

 standard year ; and that modification of the " new " from 

 the " old " style we will now explain. 



Astronomers, found, by pretty accurate calculation, 

 that the time between the sun's leaving a certain point 

 in the ecliptic and its return to that point consists of 

 365.242218 days. This differs from the Julian year by 

 .007782 of a day. Accordingly, in the time of Pope 

 Gregory XIII. (1582), astronomers observed that the 

 spring equinox (when day and night are of equal dura- 

 tion), which at the time of the Great Council of Nice (325) 

 had been on the 21st of March, then strangely happened 

 on the loth of March. Between these two dates there is 

 an interval of 1257 years. If, then, the difference 

 between the Julian, year and the mean solar year is 

 .007782 of a day, the difference in 1257 is found to be 

 9.7819 days. This accounts for the ten days. Thereupon 

 Pope Gregory ordered ten days to be omitted in that 

 year. 



But an adjustment had to be made for the future t© 

 prevent the recurrence of the error. He saw that adding 

 a day to every fourth year was too much, and that in 

 400 years the error would amount to 3'ii28 days. Ac- 

 cordingly he ordered that for the future in every 400 

 years three of the leap-years .should be omitted. This 

 was done by fixing on those which complete a century ; 

 and in the case when the number that expresses the 

 century is exactly divisible by 4, the leap-year is to be 

 allowed, but in the other three it is to be omitted. 

 Except in these centuries, 1700, 1800, 1900, all the years 

 whose numbers are exactly divisible by 4 from 1600 ta 

 2000 are leap-years. 



Last leap-year occurred in 1884, and then there were 

 five Sundays in February. When will that occur again ? 

 If it be observed that 1900 is not a leap-year it can be 

 easily found that the "charmed" year will be 1920. 



THE GASTRIC JUICE AFFECTED BY 

 SLEEP. 



DR. P. V. BURJINSKI, of St. Petersburg, has made 

 some investigations on the effect of sleep upon the 

 acidity of the gastric juice. He estimated this acidity 

 by means of a standard solution of soda, and he tested it 

 also for hydrochloric acid. The best test for the latter 

 he found to be phloroglucin-vanillin. As, however, this 

 cannot be used when there is any yellow colour in the 

 fluid to be tested, the subjects of the experiments were 

 fed on the whites of eggs, all the yolks being carefully put 

 aside. The result of numerous tests showed that during 

 the night the gastric juice is less acid than during the 

 day. Care was of course taken that the conditions re- 

 garding food were the same during the night as during 

 the day. Dr. Burjinski also found that the amount of 

 acidity varied directly with the amount of hydrochloric 

 acid present. 



