As the sun sets, in the wilderness and under the awning, Fang Xuanling, dressed in official uniforms, sat on the bench and chatted with a few men in casual clothes. They were holding information in their hands and chatting while watching. A few plates of mosquito coils were lit around the straw shed, and the white smoke was mixed with a faint fragrance.

This new mosquito coil made from pyrethrum as the raw material has a good mosquito repellent effect and does not smell bad, so it is promoted very quickly. As the scope of pyrethrum planting in various places has expanded rapidly, more and more new mosquito coils are sold on the market.

Fang Xuanling is very familiar with this new mosquito coil, because most of the officials and families in Chang'an City use new mosquito coils. When mosquitoes rage in summer and autumn, mosquito coils "keep the house" and mosquitoes dare not approach them.

Now, in this wilderness with grass and trees, there will be many mosquitoes flying near dusk, which can make people covered in bags. However, because of the lit mosquito coil, more than 30 people inside and outside the awning are leisurely and contented.

The sky is getting darker and everyone stays in the wilderness and does not go back. Of course, they are not waiting to watch the celestial phenomena at night. Everyone's attention is in the West, where is the direction of "disappearing" at one end of the experimental railway.

Soon after, a "train" will whistle along the railway.

The so-called "train" is a vehicle driven by steam. It is named "train" because when walking, the steam boiler chimney is fired and smoked on it.

Fang Xuanling was ordered by the prince to go to Xiakou for business. One of the tasks was to confirm the progress of the train development.

Steam machinery is very complicated. Fang Xuanling certainly did not understand steam engine technology before, but since he was the assistant of the prince and the prince is now in charge of the development of the train, he must learn it now.

By staying up late to read books for more than half a year, Fang Xuanling roughly understood the technical principles of the train and the technical difficulties he is facing now. Now, he is here to see with his own eyes what speed the experimental train can achieve on this experimental railway using the latest technology improved.

Their location is in the southern suburbs of Xiakou City. There is a circular railway with a circumference of forty miles, which is an experimental railway.

This "iron circle" with a circumference of 40 miles is an "experimental base" controlled by the government. Soldiers guarding, patrolling, idle people are not allowed to enter without permission.

The "experimental base" is like a small town, with workshops and dormitory areas, and many technicians and related staff live.

There are several railways connected to the "outer ring" railways into a system, and several technical research teams are also conducting the development of "trains" on these railways.

There are often "trains" on the circular experimental railway outside the experimental base. More than 20 years have passed since the completion of the experimental railway, and many trains walking on the track have been replaced.

Steam-powered steamships are now sailing in rivers, lakes and seas. However, the trains "born" at the same time are still trapped in this experimental railway, like a toddler, moving their paces with difficulty.

Looking at the colorful world outside, I was longing for it, but I couldn't take the steps to go out.

It was getting darker, and a technician lit a calcium carbide lamp and hung it under the awning. Fang Xuanling used the light to look through the information in his hand.

This material is equipped with illustrations, which records the development process of the train. Fang Xuanling has read it many times and can be said to be very familiar with it.

When the emperor was still in the secret residence, the technicians were studying trains, steamships, and these two types of steam engine devices, one was walking on land and the other was running in the water, but the development progress of the steamship was far ahead of the train.

What is the problem?

It is because if you want the steam engine to have enough power, you must have enough steam, which means that the steam boiler must be large.

However, the size of the boiler cannot be increased without limitation because the boiler itself has its own weight (including boiler water and coal). If the increase in the boiler's own weight exceeds the increase in power, even if the train can move, it can only "leave" slowly, making it difficult to "run".

The contradiction between weight and power is like a ignorant apprentice kneading dough. Add more water to the dough and more water to the dough. The consequence of poor control is that the dough is getting bigger and bigger, but it can never become shape.

For ships, because the hull is spacious enough, the size limits for steam boilers and steam engines are relatively small. Marine steam boilers and steam engines can be made larger, so the power will naturally increase.

But trains cannot do it. Because the body size is limited, there are strict restrictions on the size of steam boilers and steam engines (cylinders).

At the same time, the steam engine will vibrate when it is running. If there is no effective shock absorption structure or shock absorption device to alleviate the continuous vibration generated by the entire power system, then both the hull and the car body will not be able to bear it.

Either the structure is deformed, or the hull/body is cracked or disintegrated.

However, because the hull is large enough to accommodate shock absorbing structures or devices, it can greatly alleviate vibration problems; due to the size of the train, the space left for shock absorbing devices is limited, which brings a series of new problems.

Efficient and durable shock absorbers cannot be "get on the car", so they can only rely on strengthening the body structure strength to handle them. However, strengthening the body structure will lead to a significant increase in the weight of the body.

At the same time, if the train "runs", it also puts forward strict requirements on the durability of the wheels and axles. If the wooden wheels and axles are replaced with iron wheels and axles, the weight will be raised.

It is precisely because of the many technical problems that the development of trains has been unsuccessful. The steamship developed almost simultaneously has been practical, and has been improved from paddle wheel propulsion to propeller propulsion.

While the steamship was running happily in rivers, lakes and seas, the train was still learning to walk on the experimental railway outside Xiakou City.

However, with the continuous improvement of steam engine technology of steamships, it can be used for the improvement of trains. The "small" automotive steam boilers based on marine steam boilers have already been produced in the spring of this year.

At the same time, with the advancement of metallurgical technology and manufacturing processes, lighter and more durable automotive cylinders have been manufactured by technicians, and a series of technological advancements are used on new models of experimental trains.

Fang Xuanling took out his pocket watch to check the time. It was eighteen o'clock in the afternoon, and there was a roar of machinery in the distance.

Everyone looked up and saw a constant stream of smoke appearing at the western end of the Experimental Railway. When they looked closely, they saw a rail car moving slowly.

At the front end of the track car is a vehicle with thick smoke. This vehicle is more like a horizontal boiler equipped with wheels. Hu Chi and Hu Chi spits thick smoke and drags the eight carriages behind it forward.

The people sitting on the bench in the pergola stood up, took out their pocket watches, looked at the train gradually approaching, and looked at the time on the pocket watches.

When the train slowly passed in front of the awning, Fang Xuanling quickly calculated the average speed of the train based on the start and end time of the train walking through the lane, then walked forward and "walked side by side" with the train, and asked the "driver" on the train:

“How is the boiler?”

The driver, the person in charge of the steam engine, is the "trainer" of the train. At this time, the "driver" located in the cab of the car poked his head out and replied loudly: "Go back to join the army, everything is normal for the boiler!"

"How is the water temperature?"

"The water temperature is normal!"

“Where is the steam pressure?”

“The steam pressure is normal too!”

Fang Xuanling walked like this, walking side by side with the train walking on the railway tracks. Other technicians also followed, watching the normal train, and were happy.

The experimental train dragged eight cars and continued to circle around the experimental railway for a day and night at an average speed of fifteen miles per hour (stop to add coal and replenish water for no time).

The boiler is normal and the body is normal (at least it looks normal), which means that the durability of the experimental train has achieved the expected goals.

The average speed of fifteen miles per hour means that the driving speed of the experimental train is about the same as that of the walking speed of adults.

Such speed is not even comparable to horse-drawn railcars, and it has no practical significance.

Fang Xuanling looked around and saw everyone nodding, then shouted loudly to the "driver" on the train: "Start now, add coal, drive with all your strength!"

"Get orders!"

After the "driver" agreed, he called the "steel" to start adding coal.

The fire became stronger and stronger, and the train roared, spraying thick smoke and steam, and the movement speed gradually accelerated.

Fang Xuanling and others were able to "go side by side" with the train at the beginning. Soon, they had to speed up to keep up. After a while, they had to trot.

Then run quickly.

A group of people ran quickly, barely following the speed of the train. After running for a while, they couldn't hold on, so they stopped one after another.

Fang Xuanling almost cheered excitedly as he looked at the train that continued to move forward quickly.
Chapter completed!