March 4, i 



NA rURE 



411 



THE GERMAN NAVAL OBSERVATORY 

 Alls dent Archiv der Deutschen Seewarte. VI. Jahrgangj 



1883. Herausgegeben von der Direcktion der See- 

 warte. (Hamburg, 18S5.) 

 'T'^HIS, the si.xth yearly report of the German Naval 

 -L Observatory at Hamburg, of which Dr. Neumayer 

 is the Director, contains much valuable information as to 

 the increasing and successful application of scientific 

 methods and results to the safe navigation of the German 

 Imperial and iVIercantile Navies, in addition to the usual 

 details as to the personiu-l and working of the whole 

 establishment. 



The volume contains four papers, but the first is that 

 in which the most general interest is likely to be taken, 

 the other three referring to special reports on subjects 

 connected with one or other of the four departments into 

 which the work of the Observatory is divided. 



Commencing therefore with the first paper, there will 

 be found a general report showing much activity in the 

 collating and distribution of information on the important 

 subjects of meteorology, magnetism, and geography, and 

 describing the arrangements for making the observations 

 in the head Observatory at Hamburg, and the affiliated 

 stations on the coast. It may also be noticed that one of 

 the principal additions to the Observatory in 1SS3 was an 

 instrument for the systematic observation of refraction, 

 but the description is deferred to another report. 



Following the general report is an account of the work 

 accomplished in each of the four departments before 

 mentioned. 



Department I. is devoted principally to maritime 

 meteorology, and it will be found that the system adopted 

 ollows closely on the lines of our own Meteorological 

 Office in the collection of observations on the coast and 

 at sea, and publication of results. 



In Department II. the work resembles in some par- 

 ticulars that which is now making Kew Observatory such 

 a valuable aid to the nautical world in the testing of 

 sextants, barometers, and thermometers. At the Ham- 

 burg Observatory, however, they also prove compasses, 

 compensating magnets, log-glasses, and position lanterns 

 for ships' use. 



It may be remarked in passing that the production of 

 a novel form of compass by Sir William Thomson in 

 1876, and the full e.\p!anation by him of the principles 

 involved in its construction in several lectures, accom- 

 panied by the subsequent success of that instrument in 

 its later form, has had a world-wide influence in modify- 

 ing the previously conceived ideas of the best form of 

 compass for navigational purposes. For example, at 

 p. 32 of the first paper there will be found the announce- 

 ment of a new compass constructed in 18S2 under the 

 supervision of the Director of the Observatory in which 

 all the principles of the Thomson compass have been 

 carefully retained, but with certain changes securing 

 greater strength in the compass card. These changes 

 were introduced in view of the consideration that the 

 Thomson card was too fragile to stand the rough handling 

 it might be subjected to on board ship. This new compass 

 has been patented in Germany, and after considerable 

 trial in their mercantile marine has proved successful. 



But this department has also turned its attention to the 

 instruction of officers in the magnetism of iron ships by 



approved teachers of navigation, and at pp. 32 and 33 

 information is given as to the number of ships swung for 

 deviation of the compass by the officials of the Observa- 

 tory, and their compass arrangements scientifically treated, 

 also of the large number of ships' compass journals sent to 

 the Observatory for discussion. When the journals have 

 been examined, instructions for the future guidance of the 

 captains of the several ships are given as to the probable 

 deviations of their compasses in the ensuing voyage. 



As a useful aid to this scientific exatnination of ship's 

 compasses, the terrestrial magnetic elements with the 

 annual change are given for certain ports on the German 

 coast. 



In Department III. the important work relating to 

 weather forecasts, coast meteorology, and storm warnings 

 is carried on, and tables are given showing the number of 

 days on which forecasts w-ere given for inland and the 

 coast, and of the degree of accuracy attained. 



In 1 883 the first attempt in establishing a limited night 

 service for issuing storm warnings at night was com- 

 menced, a lantern showing a red light being hoisted as 

 the signal. 



Department IV. conducts all matters relating to the 

 trial of chronometers, and an account is given of the trial 

 of several descriptions of those valuable instruments, as 

 well as of an apparatus for simulating the action of a ship 

 in a seaway upon them, the effect of temperature being 

 observed at the same time. 



Six chronometers of the German Navy have been tried 

 in this apparatus, but the results are not reported. It 

 may be a matter of curiosity to hear how far this apparatus 

 has been a success, but long and varied experience in 

 England has shown that if the rate of a chronometer due 

 to the elements of time and temperature are properly 

 ascertained and furnished to the seaman, he will soon 

 find out the effects of the ever-varying motion of his 

 ship at sea with a precision which an apparatus on shore 

 is not likely to attain in advance. 



At p. 43 some useful information is given respecting the 

 scientific work carried on independently by the several 

 departments of the Observatory. 



Paper No. 2. — This has been written as a guide for 

 popular instruction in the nature of the deviations of the 

 compass in iron ships by means of a model. A woodcut 

 of the model is given, and the results of some twenty-seven 

 experiments recorded. Models of a similar kind are in 

 use in England and America, and are found very useful in 

 imparting practical information concerning the causes and 

 correction of the deviations of ships' compasses. 



In Paper No. 3 there is a discussion of a series of 

 observations of the magnetic declination in Barth, made 

 during the years 1881-2-3-4, a period of time which should 

 render them interesting to magneticians. 



The fourth and last paper consists of a special report 

 on the trials of marine chronometers sent in by different 

 makers, and of varied construction, during the three 

 years 1880-S3. The results of these trials are here 

 mathematically discussed, and chiefly by the use of M. 

 Villarceau's formula for rate, in which the rate ^ of a 

 chronometer is considered to be a function of the two 

 independent variables—/, the time, and 6, the tempera- 

 ture. The tables of rates recorded resemble very closely 

 those published by the Greenwich Observatory, with the 



