"History Class" What is the lecture mainly about?

[Narrator] Listen to part of a lecture in a history class.
[Professor]
    Frontier home design in the United States was greatly influenced by the provisions of the Homestead  Q29
Act of 1862. The legislation gave settlers the right to open land but mandated that homesteaders build
a structure that was at least ten by twelve feet and included at least one glass window, and they had to
live on their homestead and improve the land for five years before their claim was recognized. Of
course, when they first arrived, most homesteaders lived in their wagons or pitched tents until they filed
claims and planted Crops. And even then, knowing that fully half of the homesteaders wouldn’t make it
through the five years required to complete their claims, homesteaders tended to view the construction
of their homes as semi-permanent dwellings... more likely they’d build something better later or try to
improve on what they’d built initially if they made it through the first five years. So, in addition to the
requirements in the Homestead Act, the settlers needed a home that was easy to build, cheap, and
maybe even disposable.
    Well, the log cabin is the construction that comes to mind when we think of Western settlements, but  Q30
the plains and the prairies had so few trees that log construction was almost impossible. So the sod
house was a practical solution for homesteaders on flat, treeless land. So how do you build a sod house?  Q31
Well, first you wait for a rain that makes the earth soft, then you use a sod cutter to form sod bricks about
two or three feet square and a few inches thick. Then, you stack the bricks to form walls, and weave  Q34
branches or twigs and grass into a roof that’s finally covered with sod as well. Now, there were tremendous
advantages to this type of construction. In the first place, it was very cheap... there are journals  Q32
from the 1800s that document construction prices at about $2.50, and most of that was for the
window. And, it took very little time to build, probably a day or two. And the thick walls actually kept the
house quite cool in the summer and fairly warm in the winter. If a better home could be built later, the sod
house would simply dissolve into the soil. But there were serious disadvantages as well. Even well-built
roofs leaked onto the dirt floors, forming mud puddles, and sometimes the roof even collapsed from the
water weight. Or, in dry spells, the dirt crumbled from the roof into the home. Not to mention the infestations
of insects and even snakes that inhabited the dirt walls.
    So, those settlers who arrived in wooded areas opted to build log cabins instead of sod homes. Like  Q31
the sod construction, the log cabin could be built in a few days, using simple tools, often only an axe. But
it was much more comfortable. There’s evidence that the first log cabins were introduced by Swedish
settlers as early as the 1700s but other immigrant settlers quickly adopted the construction. First, you  Q34
build a foundation of rocks to keep the logs away from dampness that might cause them to rot. Then,
you cut down the trees and square off the logs, cutting notches in the top and bottom of each end so
they could fit together when they were stacked at the corners and it also had the advantage of assuring
structural integrity. And there were several types of notching techniques that were used, depending on
the skill of the builder. In any case, with notching, no nails were required and that was good since nails
had to be shipped into towns and then transported out to the new settlements. But there were gaps in  Q34
the walls so these had to be filled by a technique called chinking. In chinking, grass, hay, moss and mud
were worked into rolls about a foot long and maybe four inches wide and then they were inserted into
the cracks between the logs. These rolls were commonly referred to as mud cats and were very effective
in keeping out the cold and keeping in the heat. Of course, the tighter the logs, the fewer chinks
were required, and that’s important because the chinks were the weakest part of the cabin, and with the
expansion and contraction that resulted from freezing and thawing, well, chinking tended to deteriorate
and needed constant maintenance and repair.
    Okay, there was usually a stone or brick fireplace along one wall. And the roof was usually made of
wood shingles. So you can imagine, this was quite an improvement over the sod house. The advantages
were that the home could be kept clean. Even though the floor was usually dirt or gravel because
flat boards were difficult to obtain, it was still an effective shelter to keep out the rain and dust.
    Later, at the end Of the 1800s, when the railroads brought materials such as asphalt shingles, tar  Q33
paper, and finished boards to the frontier, the sod house was abandoned for one-room board shanties,
covered with tar paper. Whether this was an improvement is Subject to debate. For one thing, since they
were often built without foundations, the harsh winds of the prairies literally blew the shanties away. Still,
many settlers considered the shacks preferable to the old soddies even though they weren’t as easy to
heat and cool. To go back to the log cabin for a minute, the effect of new construction materials on the
log cabin was... aesthetic... as well as practical. The logs were often covered on the outside by finished
boards and on the inside with plaster, which gave the cabins a more finished look and improved
insulation. And by this time the old one-room ten-by-twelve was also being replaced with larger homes
with several rooms. The frontier settlers had weathered the hardships of their first five years, they’d
received their claims, and they and their homes were a permanent part of the great western expansion.