This gorgeous comparative is representative of the illustrative, landscape style common in the the genre in the early 19th century (1836 in this case). Making it all the more stunning, it’s far larger than many comparatives, measuring over 1 foot by nearly 2 feet.
Although more of a “picture” than the graph-like format of later comparative views, it has all the characteristics of a comparative. The most simplistic of the criteria is that it has multiple of the same type of physical feature, repeated side by side for sake of comparison of a particular trait: waterfalls compared by height. Further, the waterfalls are grouped by hemisphere, but more or less are arranged in an overlaid valley sort. That the waterfalls are arranged by height rather than their geographic position (i.e.: east to west) is critical to a comparative as it allows easy determination of the relative rank of a subject as well as approximation of its size. The pastoral scene style of this comparative automatically conveys upon it the next characteristics–simplification and continuity between the subjects. Distinct images of features positioned adjacently on a page do not add up to a comparative. Moreover, the depictions of the features are to present a reductionist image as a detailed picture would competing with the comparative aspect. (I describe the characteristics of comparatives here, too.)
The final characteristic is one often not associated with a landscape: accuracy of scale. This image is scaled correctly, although it doesn’t look it at first glance. The surface of the waters into which the waterfalls flow is hidden for the waterfalls in the background (the taller ones!), causing it to appear as though the bottom of a waterfall in the back is the top of a waterfall in the foreground, making the scale ambiguous. Add to that the sense of depth of the image, causing the eye to interpret the rearmost waterfalls as appearing smaller due to perspective. However, if the waterfalls are measured from the base of the first one to their tops, they scale correctly.
To evaluate this, I performed a scale analysis. I downloaded a high resolution image from David Rumsey. After opening the image in GIMP, I measured the distance from the bottom of the first waterfall to its top, then repeated for several additional smaller waterfalls behind it, always starting my measure from the bottom of the foremost waterfall. I plotted the measurements against the stated heights of the waterfalls and found that they fell in virtually a perfect line–the comparative is scaled linearly. (Check out David Rumsey’s record for this map: http://www.davidrumsey.com/luna/servlet/s/w6o7zx.)
Taken together, between its beauty and accuracy, this is one of the most well executed of the early comparatives.
© Peter Roehrich 2015