THE YOUNG SCIENTIST. 
61 
action on the different parts of the vibra- 
ting strings. In the ^olian harp con- 
structed by the Kev. W. Jones, the strings, 
instead of being on the outside were 
fastened to a sounding board within a 
wooden case, and the wind was conveyed 
to the strings through a horizontal aper- 
ture. Such an instrument might be used 
even in the open air. Dr. Young says : 
"To remove all uncertainty in the order 
of the transfer by means of a damp 
sponge, after which it is laid face down- 
ward on a sheet of ordinary roofing zinc, 
which has been previously cleaned by 
means of emery cloth. Both being now 
passed together under the roller of a 
small press, the transfer adheres to the 
metal plate ; but on damping the back of 
the paper it becomes easily removable, 
leaving the writing on the zinc. The face 
^OLIAN HAEP. 
of the notes in the lyre, I took off all the 
strings but one ; and on placing the in- 
strument in a due position, was surprised 
to hear a great variety of notes, and fre- 
quently such as were not produced by any 
aliquot part of the string ; often, too, I 
heard a chord of two or three notes from 
this single string. Discords are also often 
heard from the unison strings of this in- 
strument; the cause of which is evident 
from the manner in which the notes are 
generated; for the aliquot parts of a 
string contain in themselves an infinite 
variety of discords." 
Zincography for Amateurs. 
IN a recent paper read before the London 
Society of Arts, Mr. Thomas Bolas, 
P.C.S., described zincography as a simple 
and easy mode of printing in the follow- 
ing fashion : Zincography, he said, is 
similar to lithography, except that a zinc 
plate is employed in the place of the 
lithographic stone. The so-called transfer 
paper is merely a moderately fine paper 
which has been brushed over on one side 
with a mucilaginous mixture, prepared by 
boiling together the following: Water, 
1000 parts ; starch, 100 parts ; gamboge, 6 
parts ; glue, 1 part. This paper is written 
upon with the ordinary commercial litho- 
graphic writing ink, which has been 
rubbed up with water like an artist's 
water-color. The writing being dry, it is 
necessary to moisten somewhat the back 
of the zinc plate is now gently rubbed 
over with mucilage of gum arable, which 
is all the better for being slightly sour, 
and the excess of gum having been 
sponged off, an india-rubber inking roller 
charged with ordinary printer's ink, is 
passed over the still damp zinc i)late a 
few times. The ink takes only on the 
lines of the transferred writing, and it is 
merely necessary to lay a sheet of white 
paper on the plate and to pass both 
through the press to obtain an impres- 
sion—an exact reproduction of the original 
writing. Any number of copies can be 
printed by repeating the operations of 
damping and inking. The zincographic 
process, thus simplified, is rapid, eco- 
nomical, and within the reach of every 
one. 
Antique Bronzing and its Imitation. 
The deep green, blue, and blue-green covering 
of copper and bronze which develops under the 
influence of dampness and air, is technically 
called ^3atina, and consists of carbonate of cop- 
per. It has been observed that bronze statues 
in large towns are no longer covered with this 
patina, but turn black, while those statues which 
have been erected in the country and in parks 
are still covered with the greenish covering. 
Some kinds of bronze turn green sooner than 
others, which is specially the case with those 
containing much zinc, little lead, and no tin. 
The principal thing, however, in a statue, is a 
clean surface, which has been obtained by filing, 
etching, and polishing, and which is retained by 
frequent washing with water. In some places 
