We live in a town with three beaches. There are two parks less than 10 minutes' walk from home where neighbourhood children gather to play. However, what my children want to do after school is pick up a screen — any screen — and stare at it for hours. They are not alone. Today's children spend an average of four and a half hours a day looking at screens, split between watching television and using the Internet.

In the past few years, an increasing number of people and organisations have begun coming up with plans to counter this trend. A couple of years ago, film-maker David Bond realised that his children, then aged five and three, were attached to screens to the point where he was able to say "chocolate" into his three-year-old son's ear without getting a response. He realised that something needed to change, and, being a London media type, appointed himself "marketing director for Nature". He documented his journey as he set about treating nature as a brand to be marketed to young people. The result was Project Wild Thing, a film which charts the birth of the Wild Network a group of organisations with the common goal of getting children out into nature.

"Just five more minutes outdoors can make a difference," David Bond says. "There is a lot of really interesting evidence which seems to be suggesting that if children are inspired up to the age of seven, then being outdoors will be a habit for life." His own children have got into the habit of playing outside now: "We just send them out into the garden and tell them not to come back in for a while."

Summer is upon us. There is an amazing world out there, and it needs our children as much as they need it. Let us get them out and let them play.

    Look to many of history's cultural symbols, and there you'll find an ancestor of Frosty, the snowman in the movie Frozen. It appeared on some of the first postcards, starred in some of the earliest silent movies, and was the subject of a couple of the earliest photos, dating all the way back to the 1800s. I discovered even more about one of humanity's earliest forms of life art during several years of research around the world.

    For example, snowmen were a phenomenon in the Middle Ages, built with great skill and thought. At a time of limited means of expression, snow was like free art supplies dropped from the sky. It was a popular activity for couples to leisurely walk through town to view the temporary works of chilly art. Some were created by famous artists, including a 19-year-old Michelangelo, who in 1494 was appointed by the ruler of Florence, Italy, to build a snowman in his mansion's courtyard.

    The Miracle of 1511 took place during six freezing works called the Winter of Death. The city of Brussels was covered in snowmen—an impressive scene that told stories on every street corner. Some were political in nature, criticizing the church and government. Some were a reflection of people's imagination. For the people of Brussels, this was a defining moment of defining freedom. At least until spring arrived, by which time they were dealing with damaging floods.

    If you fear the heyday of the snowman has passed, don't worry: I've learned that some explosive snowman history is still being made today. Every year since 1818, the people of Zurich, Switzerland, celebrate the beginning of spring by blowing up a snowman. On the third Monday of April, the holiday Sechselauten is kicked off when a cotton snowman called the Boogg is stuffed with explosive and paraded through town by bakers and other tradesmen who throw bread to the crowds. The parade ends with the Boogg being placed on a 40-foot pile of firewood. After the bells of the Church of St. Peter have rung six times, representing the passing of winter, the pile is lit. When the snowman explodes, winter is considered officially over—the quicker it is burnt down, the longer summer is said to be.

Can a small group of drones（无人机）guarantee the safety and reliability of railways and, at the same time, help railway operators save billions of euros each year? That is the very likely future of applying today's "eyes in the sky" technology to making sure that the millions of kilometres of rail tracks and infrastructure（基础设施）worldwide are safe for trains on a 24/7 basis.

Drones are already being used to examine high-tension electrical lines. They could do precisely the same thing to inspect railway lines and other vital aspects of rail infrastructure such as the correct position of railway tracks and switching points. The more regularly they can be inspected, the more railway safety, reliability and on-time performance will be improved. Costs would be cut and operations would be more efficient（高效）across the board.

That includes huge savings in maintenance costs and better protection of railway personnel safety. It is calculated that European railways alone spend approximately 20 billion euros a year on maintenance, including sending maintenance staff, often at night, to inspect and repair the rail infrastructure. That can be dangerous work that could be avoided with drones assisting the crews' efforts.

By using the latest technologies, drones could also start providing higher-value services for railways, detecting faults in the rail or switches, before they can cause any safety problems. To perform these tasks, drones for rail don't need to be flying overhead. Engineers are now working on a new concept: the rail drones of the future. They will be moving on the track ahead of the train, and programmed to run autonomously. Very small drones with advanced sensors and AI and travelling ahead of the train could guide it like a co-pilot. With their ability to see ahead, they could signal any problem, so that fast-moving trains would be able to react in time.