We've all heard of horsepower, but what about Dog Power? Yes, just leash the family pet to the treadmill and the Dog Power generator will run the Blanchard butter churn, a grinding stone, a sausage cutter, or any light machine with a belt. All for only $25.

Or so the advertisement claims.

The Dog Power is just one of many machines, tools, lamps, bicycles, pieces of furniture, and other items advertised in an exhibition of 19th-century trade catalogs at the Business School's Baker Library.

The exhibition, "Marketing in the Modern Era: Trade Catalogs and the Rise of 19th-Century American Advertising," is on display in the Baker Library lobby through April 30.

Though it contains just about 40 pieces, the exhibition covers a lot of ground. It shows not just unusual products like the dog- powered generator, marketed in an 1876 catalog by Wheeler and Melick Co. of Albany, N.Y., but it also traces products that transformed American life, like one of the first steam engines for agricultural use, marketed on the preceding page in that same catalog.

Other such transforming developments represented in the exhibition are the railroads, which brought distant parts of the country closer together, and electricity, which not only lit up the night, but also provided power for motors running all types of newfangled machines.

"The 19th century saw a revolution in social and cultural history, and in business and industrial history, all reflected in trade catalogs," said Karen Bailey, rare book librarian in the Baker Library's Historical Collections Department and curator of the exhibition.

The exhibition was drawn from the 2,000 or so items in the Library's trade catalog collection. Trade catalogs are similar to the retail catalogs of today, often illustrated and describing consumer and industrial products. Like today's catalogs, they were intended to be used and eventually thrown out, but they were usually kept around longer than they would be in today's disposable society, Bailey said. Some manufacturers not only invested in elaborate printing, they also had the catalogs produced with hard covers, so customers could keep them. Prices were updated in these more elaborate catalogs by sending updated price lists for catalog items, rather than by issuing a new catalog.

Bailey said the trade catalogs provide a unique window into 19th-century life, both at work and at home. The exhibition, she said, traces several interconnected developments that transformed American life and ushered in a more modern lifestyle.

The Industrial Revolution was a huge force for change, spawning major industries like the railroads and steam engine manufacturers, as well as smaller, supporting industries that made everything from nuts and bolts, to surge protectors and the woven covers for electrical wires.

The new businesses and technology, such as the railroads and the telegraph, brought people and markets closer together. New methods of manufacturing brought down the prices of goods and, for the first time, put luxury items within reach of ordinary people.

The latter part of the century saw a general increase in wealth, Bailey said, reflected in catalogs that for the first time began targeting consumers in addition to retailers. As new manufacturing technology brought down the prices for "luxuries" like refrigerators, fancy dishes, and stylish furniture, competition for the consumer dollar increased.

The concept of leisure time, Bailey said, began to extend beyond the wealthy to the growing middle class. That change was also reflected in the catalogs, which began advertising everything from phonographs to exercise equipment to bicycles.

The catalogs don't just show products, they also show advances in 19th-century printing and binding technology. Machine presses and advances in lithography, as well as the introduction of cloth and machine-stamped decoration in bindings, drastically reduced the cost of producing enticing catalogs. These changes also made books less expensive, which combined with a rise in literacy to fuel an especially lively market in small "gift books."

With a collection as large as the Baker Library's, the difficulty wasn't finding catalogs to put into the exhibit, but deciding what to leave out, Bailey said.

The exhibit has its own site on the World Wide Web, accessible from the Baker Library's site at http://www.library.hbs.edu. The site includes an overview of the exhibition and pictures of many of the items on display, as well as a comprehensive bibliography of primary, secondary, and Web resources for studying trade catalogs. For future exhibits, Bailey said, she hopes to include in the Website all the material in the exhibit, creating, in essence, a permanent exhibit in cyberspace.