He escaped easily enough from the boys who followed his footprints in London. But his adventures were by no means over. He had chosen a bad time of the year to wander about London without clothes. It was mid-winter. The air was bitterly cold and he could not do without clothes. Instead of walking about the streets he decided to slip into a big London store for warmth.

     Closing time arrived, and as soon as the doors were shut Griffin was able to give himself the pleasure of clothing and feeding himself without regard to expense. He broke open boxes and wrappers and fitted himself out with warm clothes. Soon, with shoes, an overcoat and a wide-brimmed hat, he became a fully dressed and visible person. In the kitchen of the restaurant he found cold meat and coffee, and he followed up the meal with sweets and wine taken from the grocery store. Finally he settled down to sleep on a pile of quilts.
The scientist then easily escaped from the boys who had followed him in London. The narrator then says that his adventures were not yet finished. In addition, the narrator says about the scientist's state of mind. He said that the scientist had chosen the wrong time to roam in London since it was winter season and the air was bitterly cold. As the wind was extremely heavy, the scientist could not do anything without wearing clothes. The scientist decided not to roam outside the street to safeguard himself from the bad weather. So he decided to stay inside a big London store for warmth.

When the scientist entered the store, it was time to close the shop. The store's doors were shut, and nobody was inside the shop. He felt the pleasure of wearing new clothes without paying for them. He broke the boxes open using force. Then he tore the wrappers from the box and dressed in warm clothing. He became visible again as he wore shoes, an overcoat and a hat. From here, one can understand that the scientist becomes visible when he dresses up or covers anything over him. If he is in his bare body, he won't be visible to anyone.

Later, the scientist found some cold meat and coffee in the kitchen of the London store. After consuming that, he followed up the meals with sweets and wine from the grocery store. After finishing his big dinner, he finally settled down to sleep on a pile of quilts.
Meanings of the difficult words:
Adventure An unusual and exciting or daring experience
Wander Walk or move in a leisurely or aimless way
BrimThe bottom part of a hat that sticks out all around the head
WrapperA piece of paper, plastic, or other material that covers and protects something
Overcoat A long thick coat was worn in cold weather
Grocery A store that sells food and small things for the home
National Council of Educational Research and Training (2007). Footprints without Feet - H.G. Wells(pp. 26-31). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.