This is an interesting question with an interesting answer. There are two ways Derozio's poem can be analyzed. The second way of analyzing it provides structural support for Dervozio's anti-colonizer stance. In the poem, Dervozio suggests blame belongs to the colonizers for the loss of India's literal, and metaphorical wealth. He likens India to an eagle who is captive, with pinion feathers chained down, grovelling in the dust in servitude:
Thy eagle pinion is chained down at last,
And grovelling in the lowly dust art thou,
There are three classic structures for sonnets, though there may be unlimited variations sonneteers. The original form is Petrarch's. His structure is an octave followed by a sestet. This means there are eight lines followed by six lines for a total of fourteen lines. That octave introduces a problem or complaint and the sestet offers the paradox (i.e., seemingly untrue contradictory idea) in the resolution. Some people prefer to call the octave two quatrains, but Petrarch wrote the first eight lines as a unit making it is more accurate to analyze the structure as octave and sestet. It is said that Petrarch never ended his sonnets with a couplet (i.e., two rhyming lines). Petrarch's rhyme scheme has a set scheme for the octave: abbaabba. Yet there are a number of options he used for sestet, for example, cdcdcd or cdecde.
The Shakespearean structure is the most well-known. This structure is also called the English sonnet form. The structure is three quatrains (twelve lines) and a rhyming couplet for a total of fourteen lines. The rhyme scheme is a set abab cdcd efef gg. The two breaks between the three quatrains (i.e., called a volta, or a turn) allows for a change of subject within the topic of the sonnet. The couplet allows for the paradoxical resolution to the problem or contemplation presented in the quatrains.
The Spenserian sonnet is similar to the Shakespearean with three quatrains and an ending couplet (fourteen lines) but the rhyme scheme has a special feature that allows for a continuous discussion of the topic throughout without a change in subject. The ending couplet allows for a paradoxical twist in the resolution. The rhyme scheme of ababbcbccdcd ee has "linked" quatrains because of the repeated rhyme at lines 4 and 5 and again at lines 8 and 9. This linking is called concatenation and allowed Spenser to develop longer problems or contemplations.
Dervozio's rhyme scheme is not like any of these. His rhyme scheme is an original variation. While it might be analyzed as three quatrains and a sestet with an ending couplet, abcb cbdd efef dd (fourteen lines), it might also be analyzed as a sestet followed by a couplet, a quatrain, and another couplet: abcbcb dd efef dd. If you look closely, you'll see that there is a double couplet in abcbcb dd efef dd. A sestet precedes the first dd couplet and a quatrain precedes the second dd couplet. Thus the Petrarchan sestet is at the beginning. The Shakespearean form is varied with two couplets. These breaks with European form add structural support to Dervozio's message in opposition of European colonizers. You might also say the structure resembles Shakespearean form with a double couplet like Spenserian form.
italian/petrachian sonnet is used in this poem written by derozio.