The times., 1899-12-01
THE WIRELESS TELEGRAPH.
Interesting Experiments ny Prof
Hammei, OF Baltimore.


HammeI, of Baltimore.
BALTIMORE, Nd, Nov. 3O-Prof. ". c.
A. Hammel. OF the department OF physics OF
the Maryland State Normal School. is inter
ested in experiments in the field Of wireless
telegraphy. Thus far his experiments have
been very successful, and be saws he has
succeeded in overcoming the induction
caused by electric wires sufficiently to com
municate readily with his home. one and
half miles from the Normal School
Professor Hammel says telegTaphy
without wires has heretofore been limited
10 sending messages over water or eX-
panses on land where there were no electric
wires to interfere with the electric waves
in the atmosphere. To overcome this OBJ
stacle TO the successful use OF the wireless
telegraphy in cities where necessarily there
IS multiplicity Of wires charged with cleo
tTiclty has been the aim OF Professor Ham
mel. In all Of his experiments he followed
the lines laid down by Preece. Lodge, and
Mareoni
The apparatus used by Prof Hammel
is simple, and is not nearly as complicated
as that used by his predecessors in the field
Of wireless telegraphy. II consists OF a re-
ceiver, bell, and relay. the receiver and re-
lay being OF the type used in ordinary
q
TWO inches long. having an inside diameter
OF one-sixteeDth Of an inch The tube is
filed with filings Of nickel and silver in The
proportion OF 80 parts OF nickel to . parts OF
silver.
The filings are inserted at each end OF
the tube in equal quantities and forced to-
ward the middle by the use OF delicate
thumb screws. The essential point Is 70 get
the filings adjusted IN harmony with other
parts OF the apparatus, and to this end
alone Prof Hammel labOTed for four
consecutive hours. The filings perform
their function by elougatIng and connecting
the separate piles In the tube whenever the
| electric key is touched, and by returning
Immediately afterward 10 their former con-
dition
Prof Hammel gave an exhibition of the
/ working Of his method yesterday. The
I receiving apparatus was placed on table
/ in his laboFat tory, while the sending device
/ was located in a remote part Of the school
/ building. He first used a static machine to
/ generate the electricity and found that
/ with a spark hardly larger than q pin point
/ he was able 20 ring a bell IN his laboratory,
/ although the current had 10 pass through
four walls of stone and brick aggregaJing
nine feet in thickness and had also to con-
tend with iron beams, steel ceilings, and
/ the numerous electric wires in the vicinity
! OF the school building. He also. BY means
/ Of a larger spark. communicated with his
I home, one and half miles distant
/ Another delicate test was with the cleo
tric spark generated by ordinary home con-
veniences. Prof. Hsmmel has arranged his
, house with electric wires and push but
tons for the convenient lighting and turn
ing of OF gas IN the different rooms. He
placed the receiving apparatus IN MS din
ing-rOOn and found that whenever ne
[ turned the gas on or on IN any OF he
rooms the electric spark was sufficient 20
ring a bell.
Another test was made by the use Of
steel balls One is suspended from the
tower Of the Normal School and the other
from 4 frame erected on the roof OF Prof.
HammePs home. These balls have wires
running nearly to the ground but are in
sulated at each end. By the use OF the
induction coil and spark One-quarter OF
an inch in length, Prof. Hammel was ena-
bled to communicate readily with his
home and without any breaks, although
the streets were filled with network OF
trolley, electric light, and telegraph wires
| To overcome the induction caused Dy
these wires has been the effort Of scientists
interested in wireless telegraphy, and Prof
HammeI saws he has accomplished this
He reasons that if he IS able 70 ring q
bell at a distance OF one and half miles,
a smaller force will operate a telegraph
receiver. and if wireless telegraphy viii
operate successfully at that distance il
will operate equally as well at a greater
distance.
Prof. Hammel does not make secret
| of his experiments. The exhibition given
yesterday was Witnessed by Governor
Lowndes and other members OF the State
Board of Education