A lyric poem is usually short and expresses the personal emotions or feelings of the narrator. It is very rythmic, and the most common meters used in lyric poetry are iambic, trochaic, pyrrhic and anapestic. However, some lyric poems have a combination of more than one meter.
Lift Every Voice and Sing, by James Weldon Johnson, is a relatively short poem consisting of only 3 stanzas of 10, 11 and 12 lines respectively. The poem uses more than one meter, with the use of iambic meter for some lines. For example: "<em>Yet </em><em>with</em><em> a </em><em>stead</em><em>y </em><em>beat</em><em>, Have </em><em>not</em><em> our </em><em>wear</em><em>y </em><em>feet</em>"<em>.</em> There is also a lot of rhyming and repetition of patterns throughout the lines, and it deals with vivid imagery to express the emotions of the narrator. All of those elements are characteristic of a lyric poem.
The author Mary Shelley use the word chimerical in that line because she said that the powers of Cornelius Agrippa were improbable and because she wanted to say this in a fancy way.
Hope this Helps :)
BTW, Mary Shelley is the author of Frankenstein <span />