1 878.] 
On Space of Four Dimensions . 
227 
Quoting, as an appropriate final remark, the words with 
which I concluded another paper having an especial applica- 
tion to a system of ventilation: — “ I will not follow further 
the proposition to change the seasons into a perpetual spring- 
time — practical ventilation is the supply in dwellings of an 
abundance of fresh air at the several seasons, warmed to 
the temperature of comfort in winter, and supplied in quan- 
tity to the volume of comfort (as near as possible of the 
quality and condition of out of doors in the shade) in 
summer. The truth is, all our heating and ventilating 
appliances are the compromise of condition— a truth ex- 
tending beyond all mechanical operations to the phenomena 
of Nature itself.” 
VI. ON SPACE OF FOUR DIMENSIONS.* 
By J. C. Friedrich Zollner, 
Professor of Physical Astronomy in the University of 
Leipzig. 
%N the first treatise the author shows that both Newton 
W and Faraday were advocates of the theory of diredt 
^ adtion at a distance through a vacuum, in opposition to 
the views of many modem scientific men. In the last 
* Wissenschaftliche Abhandlungen von Joh. Carl Friedrich Zollner, 
Professor der Astrophysik an der Universitat zu Leipzig. Erster Band. Leipzig : 
L. Staackmann, 1878. (With portraits and facsimiles of Newton, Kant, and 
Faraday. 8vo., 732 pages.) 
CONTENTS. 
1. On Adtion at a Distance. 
2. Emil du Bois Reymond and the Limits of Natural Knowledge. 
3. Newton’s Law of Gravitation and its Derivation from the Static Effedts 
of Eledtricity. 
4. The Laws of Fridtion, and their Dedudtion from the Dynamic Effedts of 
Eledtricity. 
5. As to the Existence of Moving Eledtric Particles in All Bodies. 
6. Adhesion and Cohesion as dedudted from the Dynamic Forces of Elec- 
tricity. 
7. 8, g. The Mechanical, the Magnetical, and the Eledtrical Effedts of 
Light and of Radiant Heat. 
10. Radiometrical Researches. 
11, 12. On the Theory of Eledtric Emission and its Cosmical Application. 
13. Thomson’s Demons and the Phantoms of Plato. 
n 
Q 
