JANUARY 11, 1901.] 
of the dye be added, the sky can be strongly 
colored without apparently changing the 
color of the corona in the slightest degree, 
a rather surprising circumstance, since both 
are produced by the same means. We 
should have now a most beautiful and per- 
fect reproduction of the wonderful atmos- 
phere around the sun, a corona of pure 
golden white light, with pearly luster and 
exquisite texture, the misty streamers 
stretching out until lost on the bluish-green 
background ofthe sky. The rifts or darker 
areas due to the unequal illumination are 
present as well as the polar streamers. The 
effect is heightened if the eyes are partially 
closed. 
A photograph of one of these artificial 
eclipses is reproduced in Fig. 3. Much of 
the fine detail present in the negative is lost 
in the print, and still more will doubtless 
go in the process of reproduction. The 
- coronal streamers extend out much farther 
than is indicated by the photograph. No 
especial pains were taken to get the polar 
rays just right. TE. We, WWGG. 
UNIVERSITY OF WISCONSIN. 
SCIENTIFIC BOOKS. 
Street Pavements and Paving Materials. A Man- 
ual of City Pavements: the Methods and 
Materials of their Construction. For the use 
of Students, Engineers and City Officials. By 
GEORGE W. TILLSON, C.E., President Brook- 
“lyn Engineers’ Club, ete. New York, John 
Wiley & Sons. 1900. 
As might be inferred from the title, this is a 
very pretentious book. The design of the 
author appears to have been to exhaust the 
subject. A very careful examination of the 
book has convinced the reviewer that for the 
purpose of the reviewer the accomplishment of 
this design may be divided into two parts: (1) 
That portion of the book that comes strictly 
within the perview of the engineer, and (2) that 
portion which does not. 
Before proceeding to the consideration of 
these parts we wish to remark certain condi- 
SCLENCE. 
67 
tions that relate to the work asa whole. The 
author does not appear to have been impressed 
with the gravity and seriousness of the great 
work he has undertaken, but a certain atmos- 
phere of flippancy pervades some of the most 
important discussions ; as witness his definition 
of the word Bitumen on page 43. 
Again, either the manuscript was very care- 
lessly prepared, or the proofs were very care- 
lessly read, for the grave errors that are too 
numerous to mention can hardly be laid to the 
account of the printer. For illustration turn to 
page 53. The sentence, ‘‘ He contends that by 
the use of petroleum ether a large amount of 
asphaltene is dissolved and is consequently 
ealled asphaltene,’’ is nonsense, as it stands; 
the last word should be ‘petrolene.’ Further 
on he says, ‘‘I had to admit, and do admit, 
that the analysis as carried out by the later 
methods suffices to make identity or nonentity 
of two samples probable or highy probable.’’ 
Nonentity should be nonidentity, and highy 
should be highly. To point out all the errors 
of this description would require too much 
space. 
That portion of the work that relates strictly 
to engineering problems appears to be carefully 
prepared, and the various problems discussed 
appear to be treated with intelligence and dis- 
crimination. Had Mr. Tillson, as an engineer, 
discussed seriously and carefully read the proofs 
of a work devoted to the engineering problems 
involved in street paving, we do not doubt that 
a very valuable book would have been the re- - 
sult. For Mr. Tillson has reaped a field of 
immense extent, and he has brought together 
an immense amount of detail from widely sepa- 
rated sources and has brought them into con- 
venient form. For this his fellow members of 
the engineering profession, and a wider client- 
age of miscellaneous readers outside his profess- 
ion would have doubtless given him apprecia- 
tive thanks. But, as before stated, Mr. Tillson 
has attempted, in a very pretentious way, to 
exhaust his subject, and has wandered far be- 
yond the borders of his profession of engineer- 
ing, thereby committing the blunder of attempt- 
ing to treat subjects learnedly of which he has 
no knowledge. For engineers as a class are 
not trained in general science. They are 
