618 ADDRESS OF PROFESSOR LOVERING. 
An interesting event in the history of science, which must be 
known to many of you, has taken place during the current year. 
In 1824, Poggendorff began to edit the Annalen der Chemie und 
der Physik. Under his supervision 150 volumes have been issued, 
containing 8,850 distinct communications from 2,167 different 
authors, the 193 papers of H. Rose outnumbering those of any 
other contributor. The history of physical and chemical dis- 
covery during the last fifty years might be written out of the 
materials treasured up in this single journal. In recognition of 
the signal service which Poggendorff has hereby rendered to 
science, his friends assumed the editorship of one volume in 1874, 
which is called the Jubilee volume [Jubelband]. 
In 1826, Poggendorff described in volume vii. of his journal a 
device of his own invention for observing with exceeding nicety 
the movements of a magnetized bar. A mirror was attached to 
the bar and moved with it. From this mirror a beam of light 
was reflected into a theodolite. This was the origin of the happy 
thought of amplifying a trifling motion by making the finger 
of a long and delicate ray of light serve as a weightless pointer. 
A few years later, this idea was embodied by the mathematician, 
Gauss, in an instrument which he called the magnetometer. 
Since that time, it has been continually budding out in new appli- 
cations, scientific and practical. I need only recall to your recol- 
lection the beautiful method of Lissajous for compounding the 
vibrations of tuning-forks, and tracing in golden lines the curves 
which are characteristic of different musical intervals and varied 
phases of vibration. A new chapter has been opened in mechanics 
for describing and explaining these strange and nameless curves; 
and, in acoustics, the ear has been dispossessed by the eye of what 
would seem to be its own by right divine, and it is no longer the 
best scientific judge of sounds. By new devices Koenig has 
translated time into space and made visible the individual vibra- 
tions of the invisible air; and, in numerous ways, the mechanism 
of sound is as real to the eye as the sensation is to the ear. 
With a bare allusion to the fact that every message which 
passes over the cable telegraph is a tribute of indebtedness to the 
simple but comprehensive method of Poggendorff, I pass to tW? 
other cases of great difficulty and wide significance in which the 
same method has triumphed. I refer to the determination of 
velocity of electricity and the velocity of light. 
the 
