Complex sentence: In the estimation of 1911 Encyclopædia Britannica, Kinkel's popularity was out of proportion to his talent; his poetry is of the sweetly sentimental type in vogue in Germany in the mid- 19th century.
Split into simpler sentences: In the estimation of 1911 Encyclopædia Britannica, Kinkel's popularity was out of proportion to his talent. The "Britannica" of 1911 characterizes his poetry as of the sweetly sentimental type in vogue in Germany in the mid- 19th century.