David Tower, the senior partner of the firm, first entered the business of engineering paper mills as an apprentice millwright in 1845 at the age of 13, and eventually moved his own practice to Holyoke in 1867.
Receiving a steady stream of work, David gradually brought on other draftsmen and was joined in 1871 by his younger brother Ashley B. Tower, who he mentored as his own apprentice.
By 1878, Ashley Tower had become accustomed to the trade and an influx of business led to him being made the firm's junior partner, which became best known as D. H. & A. B. Tower.

From 1878 until 1892, the brothers Tower would produce some of their most prolific work.
During this time the brothers furnished designs on mills and mill machinery in Holyoke, from Maine to California in the continental United States, and abroad on five continents.
While an exact figure is unknown, in a cross-examination of Ashley Tower in a court case between the City of Holyoke and the Holyoke Water Power Company in 1899, Tower stated that of the mills built in Holyoke up until that time, he had been involved in the construction of 25 in some capacity, 16 of which were done in a central design role.
While it is unclear from this testimony what share of work was done by each brother and how many of those mills designed were in the seven years following David's retirement Ashley Tower stated he had worked on more than 55 mills in key engineering roles, and more than 100 in any capacity.

The brothers would also play a significant role in establishing the economic success of the Kimberly-Clark company, designing one of its earliest groundwood pulp plants in Kimberly, Wisconsin in 1888.
More significantly however, their designs for sulfite pulp mills in Appleton, Wisconsin built in 1890 gave the company a significant advantage.
With this new plant the company had the resources and geographic scale of the American Midwest, while operating the first such mill west of Pennsylvania to adopt the improved process which derived almost pure cellulose from wood pulp.

At the beginning of their partnership the firm was located in the Hadley Falls Bank Building which sat at the corner of Main and Dwight (not to be confused with the later Hadley Falls Trust Building at the corner of Maple & Suffolk), and subsequently relocated to Holyoke's Flatiron block, which was said to have had advantageous lighting at most hours of the day due to its rounded northeast-facing corner, which had windows facing in three different directions.

Originally Ashley B. Tower joined David H. as an apprentice, with no prior experience in engineering work or architecture besides a previous carpentry apprenticeship.
In time his abilities exceeded his older brother's in certain regards; of the two, he was the only one known to hold patents- by 1885, he had invented an improved wood pulp grinder which would be used in their clients' mills domestically and abroad.

One of the things that reportedly made their firm successful was their study of foreign as well as domestic designs, with reports that the Towers went abroad to Europe in 1884-1885 to examine the latest designs in paper mills on that continent.
Moreover, their firm placed a far greater emphasis on the surroundings of the sites at which their mills were constructed, rendering otherwise challenging terrain into the driving force of a mill's productivity.
Among notable examples of this is the site of the Melchert & Cia Mill in Salto, São Paulo, Brazil.
Designed and built in 1887 on the banks of the Tietê River, at the time of its construction it was regarded as a folly by locals, who mocked Melchert & Cia, its wealthy Brazilian backers, for "[the] insane idea of manufacturing paper in that country".
Designed by the brothers Tower, it became the first industrial paper mill in South America and remains a functional site even today, producing large quantities of paper for currency.

Another example of the brothers' methodical research can be found in the construction of the, since demolished, Hampden County Jail.
When first contracted for the design, t
David Tower, the senior partner of the firm, first entered the business of engineering paper mills as an apprentice millwright in 1845 at the age of 13, and eventually moved his own practice to Holyoke in 1867. Receiving a steady stream of work, David gradually brought on other draftsmen and was joined in 1871 by his younger brother Ashley B. Tower, who he mentored as his own apprentice. By 1878, Ashley Tower had become accustomed to the trade and an influx of business led to him being made the firm's junior partner, which became best known as D. H. & A. B. Tower.
From 1878 until 1892, the brothers Tower would produce some of their most prolific work. During this time the brothers furnished designs on mills and mill machinery in Holyoke, from Maine to California in the continental United States, and abroad on five continents. While an exact figure is unknown, in a cross-examination of Ashley Tower in a court case between the City of Holyoke and the Holyoke Water Power Company in 1899, Tower stated that of the mills built in Holyoke up until that time, he had been involved in the construction of 25 in some capacity, 16 of which were done in a central design role. While it is unclear from this testimony what share of work was done by each brother and how many of those mills designed were in the seven years following David's retirement Ashley Tower stated he had worked on more than 55 mills in key engineering roles, and more than 100 in any capacity.
The brothers would also play a significant role in establishing the economic success of the Kimberly-Clark company, designing one of its earliest groundwood pulp plants in Kimberly, Wisconsin in 1888. More significantly however, their designs for sulfite pulp mills in Appleton, Wisconsin built in 1890 gave the company a significant advantage. With this new plant the company had the resources and geographic scale of the American Midwest, while operating the first such mill west of Pennsylvania to adopt the improved process which derived almost pure cellulose from wood pulp.
At the beginning of their partnership the firm was located in the Hadley Falls Bank Building which sat at the corner of Main and Dwight (not to be confused with the later Hadley Falls Trust Building at the corner of Maple & Suffolk), and subsequently relocated to Holyoke's Flatiron block, which was said to have had advantageous lighting at most hours of the day due to its rounded northeast-facing corner, which had windows facing in three different directions.
Originally Ashley B. Tower joined David H. as an apprentice, with no prior experience in engineering work or architecture besides a previous carpentry apprenticeship. In time his abilities exceeded his older brother's in certain regards; of the two, he was the only one known to hold patents- by 1885, he had invented an improved wood pulp grinder which would be used in their clients' mills domestically and abroad.
One of the things that reportedly made their firm successful was their study of foreign as well as domestic designs, with reports that the Towers went abroad to Europe in 1884-1885 to examine the latest designs in paper mills on that continent. Moreover, their firm placed a far greater emphasis on the surroundings of the sites at which their mills were constructed, rendering otherwise challenging terrain into the driving force of a mill's productivity. Among notable examples of this is the site of the Melchert & Cia Mill in Salto, São Paulo, Brazil. Designed and built in 1887 on the banks of the Tietê River, at the time of its construction it was regarded as a folly by locals, who mocked Melchert & Cia, its wealthy Brazilian backers, for "[the] insane idea of manufacturing paper in that country". Designed by the brothers Tower, it became the first industrial paper mill in South America and remains a functional site even today, producing large quantities of paper for currency.
Another example of the brothers' methodical research can be found in the construction of the, since demolished, Hampden County Jail. When first contracted for the design, t
D. H. & A. B. Tower