AWDC Chapter 22
by VolareToma and Ladapole finally managed to create a compass and level that seemed usable for surveying, just as early autumn arrived.
It took almost two months after returning from the desert.
The material for the magnet itself wasn’t rare, but making a portable and easy-to-use compass was the challenge.
It was difficult to make the magnet into a thin plate and have it rotate in a balanced way.
Creating the level wasn’t easy either. Creating a thin, uniform glass tube was no simple task.
Ladapole demonstrated his dexterity in tackling both.
Toma conveyed the mechanisms of the compass and level through drawings, but when they tried to actually make them, it wasn’t straightforward.
“Well, what Toma-san is saying is just too difficult, isn’t it?”
He grumbled, but it was typical of him to happily tackle new things.
Now, they could formulate a plan to draw water beyond the Lean Ridge.
They were going to enter the desert again to survey.
In addition to the previous members, two young members from the papermaking group joined.
Sulke, who was 20 years old, and Kent, who was 19 years old.
They had worked together making paper last year, so they knew each other well and were honest.
There were other members who made paper, but they decided that it would be cruel to send young householders on a long-term business trip.
Also, the number of donkeys they were taking increased to 20.
Last time it took a month and a half, but this time they planned to spend more than two months.
Considering that they would carefully survey and take a detour to the west, they judged that it would take that long.
“Eeeh, I don’t understand trigonometry at all.”
Along the way, Toma was teaching them how to survey, as well as teaching them the four arithmetic operations and trigonometry.
Jim had been interested in the numbers Toma wrote and was enthusiastic about calculations, so he didn’t seem to mind.
However, the other members looked resigned.
Kido, from the beginning, devoted himself to taking care of the donkeys rather than studying.
Sulke was similar. He was more interested in numbers than Kido, who had thrown in the towel from the start, but he only managed to understand addition and subtraction.
Kent was even better than that, and he understood that addition and subtraction were useful for shopping.
Because of that, he didn’t dislike staring at paper and numbers.
And Ladapole could do the four arithmetic operations. However, he still didn’t understand the meaning of decimals, fractions, or trigonometry.
Even so, the concept of trigonometry was fundamental to surveying.
“Look, if you know the angles and side lengths of a triangle, you can find out the lengths of the remaining sides and angles, right?
If you apply this, you can grasp the length to a place that is far away.”
Toma talked about how useful trigonometry was, rather than the principle of trigonometry itself, to get them interested.
Apparently, Ladapole seemed to be somewhat interested.
While studying like that, they were trying to cross the desert while surveying the western side of the desert, the foot of the small mountains that run north and south.
The Datar Plateau is high in the west and low in the east. Mountains and hills continue to the west, but they gradually descend towards the east, and eventually become cliffs facing the Mulan River.
Therefore, they thought that if they put a waterway through the place they were surveying now, it would be easy to distribute water to the lowlands in the east.
The current route was also the planned construction site for the waterway and road.
It took three weeks to complete the survey up to the Lean Ridge. The purpose of this time was to find a plan to pull water into the desert by passing through the Lean Ridge.
It could be said that they had entered the full-scale surveying work.
While surveying the water source and the Lean Ridge, Ladapole said.
“After all, Toma-san, you’re thinking that digging a tunnel is the best, right?”
“Yeah, detouring around the Lean Ridge would be long, and I think the scree slopes along the way would be quite troublesome.”
Among the methods of drawing water beyond the Lean Ridge, drawing a waterway around the foot of the Lean Ridge was the easiest.
Even the village’s civil engineering technology would be enough to make it.
However, with this method, they would have to pass through several scree slopes along the way.
Scree slopes are slopes full of stones, where stones are always falling.
If they made a waterway in such a place, the waterway would often be buried with gravel. If they left it alone, the waterway would be buried in no time, and water would not enter the desert. They would have to send people to the other side of the Lean Ridge many times to secure and manage the waterway. The management costs would be considerable.
Toma wanted them to concentrate on farming rather than doing such troublesome work.
The next method they considered was that far downstream from the water source, there was a place where the Lean Ridge stopped, and they could reach the desert without climbing the ridge. Moreover, near that place, the Mulan River was narrowed by a huge rock, making it an ideal place to build a dam.
If they built a dam here, it would be easy to draw water into the desert, and they could avoid the scree slopes.
But with this method, the dam itself would be huge, and they judged that construction would be impossible from the beginning. In this place, the valley had been deeply carved by the river, and both banks were cliffs, and the required height of the dam easily exceeded 100 meters. If the dam was that high, the water pressure at the bottom would be enormous.
A dam that could withstand that much water would have to have a thick and heavy lower layer at the bottom to avoid being easily destroyed.
It would not be possible to make it strong without using concrete or stone, but it seemed impossible to collect the necessary amount of materials in this world.
In the first place, Toma had no experience in building dams. He couldn’t do structural calculations for dams.
And finally, what remained was the method of piercing the Lean Ridge with a tunnel and passing a waterway through it.
However, it was expected that digging a tunnel would also be difficult.
What Toma was worried about was that there was no surveying technology in this world.
If it was a short tunnel or waterway, it wouldn’t be a problem even if the surveying technology was immature.
However, if it became long, errors in the survey results would lead to enormous losses.
Toma had no choice but to start by improving the available equipment and manufacturing better surveying instruments.
He spent two months just for that purpose, and now he was going to start work using the surveying instruments he had finally created.
Some of the tunnels built in Japan during the Meiji era had rough plans.
In the old hand-dug tunnels, there was one that curved greatly in the middle, and another hole was opened at a high position.
They started digging from both sides of the mountain and were proceeding to meet in the middle, but they never met.
The tips of the tunnels they were digging were 3 meters apart from each other left and right, up and down.
As a result, they had to dig again, and the tunnel became a dogleg, and moreover, an extra hole was opened.
Even if it was a short tunnel of less than 50 meters, it would be like this if they dug recklessly.
If they were to dig a tunnel of more than 1 kilometer in this world without surveying equipment, it was thought that the results would be even more miserable.
Toma himself had never dug a tunnel.
But if he surveyed properly and didn’t make a mistake in the direction to dig, he should eventually be able to penetrate the Lean Ridge.
However, there were many concerns, such as whether the geology was weak and would collapse as soon as they dug, or whether it was too strong and they wouldn’t be able to dig.
He couldn’t stop worrying about what method was best.