measurably

In a measurable manner.

To a measurable extent.

During this interlude, Warwick, though he had slackened his pace measurably, had so nearly closed the gap between himself and them as to hear the old woman say, with the dulcet negro intonation: […]

Now, Bismarck and Tirpitz versus Alabama and South Dakota is not quite the same level of curbstomp as the previous battle, mainly due to the fact that, well, the second pair is gonna last - that battle's gonna last more than five minutes; however, it's still a case of, well, the South Dakota class is measurably superior to the Bismarck class in terms of total firepower, as we discussed previously.