If the 19th century science was defined by certainty, and what ways do these documents undermine that certainty? do any of these authors see this loss of the certainty as a good thing? why or why not?

If 19th-century science is defined by certainty, the experiments with advanced technology and the scientific studies would have been the poof of certainty.

19th century was a period when many ideas, theories and inventions were developing. This era was also known as a modern era of science. The result of the discovering and experimenting would have been recorded in the Journal, some of them still exist. So, there wouldn't have been any loss, whatever the scientists were putting forward were seen in the public. Some of the examples are the Steam Engine, Charles Darwin Theories, telegraph and telephone, medicines.

a, c, & d are correct:

they wanted lands to settle the extra population.

they wanted new markets for english goods.

they wanted to avoid civil war.