10 John Francis Encke. 
respectively, as measured by Ditscheiner, 590:53 and 589-89, 
which are 0°49 and 0°46 higher than those of Angstriém as given. 
in Table I. Ditscheiner in this second paper has recomputed 
the table given in his first memoir. The results are much higher 
than those of Angstrém or those given in my reduction of Dits- 
cheiner’s first measurements, the average difference being about 
‘4 of one unit. The close agreement of the two sets of results 
given in Table I appears to me a sufficient reason for adhering 
to the values of the wave lengths employed in this paper as data 
for interpolation. 
Cambridge, August, 1866. | j 
Art. Il.—John Francis Encke.* 
JOHN FRANCIS ENCKE, born Sept. 23, 1791, was the youngest 
son but one of the deacon of the Jacobi Church in Hamburg. 
Four years after his birth his father died, leaving the care and 
the education of eight children to his mother, a lady of much 
worth, and happily possessed of great mental energy. 
The first tutor of the boy was Mr. Hipp, a gentleman possess- 
ing considerable aptitude for mathematical teaching; and to his 
onor be it spoken, a man who rendered valuable pecuniary 
assistance to the orphan and moneyless family. Hipp continued 
this material encouragement to young Encke even after the time 
that he entered the College at Hamburg, well known as the Jo- 
haneum. At this College, then under the directorship of Gurlitt, 
who enjoyed a high reputation for classical learning, the boy- 
student rapidly advanced, and in addition to considerable ability 
in Latin composition, his knowledge of Greek was sufficient to 
enable him to translate and enjoy the Lyricks of Pindar. Not- 
withstanding, however, this early classical training, when the 
time came for his entrance at the University, Encke resolved 
henceforth to devote his attention mainly, if not exclusively, to 
the study of astronomy. 
ut here came a very formidable impediment; there were 
ample funds at the disposal of a poor clergyman’s son for a theo- 
logical career, but none for the prosecution of so unusual a study. 
Nevertheless, such was the acknowledged ability, and so deter- 
mined was the inclination, of young Encke, that, as is happily 
not unusual in such cases, all the difficulties yielded at length to 
perseverance, and to bis great joy, in Oct. 1811, he found him- 
self at Gottingen, and a student under the celebrated Gauss. 
rily printed in French; as a condescension, however, or as an in- 
sult to the inhabitants, a German translation was added; in a 
