370 RECORD OP SCIENCE FOR 1887 AND 1888. 



These two tables contain a wealth of data for future deductions, but 

 as to the results that Looniis draws from them, Koppen promises a fut- 

 ure communication. 



III.— THEORETICAL HYDRO- DYNAMICS APPLIED TO THE MOTION OF 



THE AIR. 



(10) Koppen, whose skill iu studying the mechanism of storms and 

 in handling masses of data has so frequently been shown, has con- 

 tributed to the Meteorological Zeitschrift of December, 1888, a study 

 " On the form of the isobars iu reference to their dependence upon alti- 

 tude and the distribution of temperature." Assuming- that isotherms 

 and isobars have been given by the daily weather chart, he then gives a 

 most convenient and rapid method of computing tables and deriving 

 the isobars for any elevation, such as 2,500 meters, by an inspection of 

 the tabular figures. Such upper isobars were first published for a given 

 storm by Mollerin the Annalen fiir Hydrog., April, 1882. The impor- 

 tance of such upper isobars had been urged by me in 1871-'72, and sam- 

 ple maps were drawu preparatory to their daily use, but subsequently 

 the introduction of departures and variations of departures in pressure 

 and temperature as auxiliary to sea-level isobars and surface isotherms 

 was decided on by General Myer. Koppen's diagrams of ideal systems 

 arc very suggestive. 



(11) Ferrel. — In 188G there appeared a treatise by Prof. William Fer- 

 rel, •' Eecent Advances in Meteorology," being Appendix 71, or part ii, 

 of the Annual Eeport of the Chief Signal Officer for 1885. This treatise 

 was originally designed as professional.i)aper of the the Signal Service, 

 No. 17, but the abolition of that series of papers by order of the Secre- 

 tary of War caused a change iu the method of publication. 



An abstract of the contents of this book was delivered in lectures by 

 Professor Ferrel to the second lieutenants of the Signal Corps, but the 

 abolition of the Signal-Service school of instruction at Fort Myer has 

 prevented its further use in that direction. The complete volume being 

 easily obtained in this country, I need give only a short account of it. 



In this work Ferrel has collected the results of recent investigations 

 by many authors, adding to them many of his own demonstrations, and 

 combining the whole into a systematic treatise on meteorology under 

 the following seven chapters : (1) The constitution and physical prop- 

 erties of the atmosphere; (2) the temperature of the atmosphere and 

 the earth's surface; (3) the general motions and pressure of the atmos- 

 phere; (4) cycloiU'S ; (5) tornadoes ; (G) observations and their reduc- 

 tions; (7) ocean currents and their meteorological effects. In the first 

 chapter, after the sections ou chemical constituents, pressure and 

 weight, there comes a section on the diffusion and arrangement of the 

 constituents, iiicluding the vapor atmosphere, followed by the ordinary 

 applications to the atmosphere of the thermodynamics of adiabatic 

 processes, hi his section on the diathermancy and transparency of the 



