The feeling that the author is trying to communicate via this imagery is one of repressed feeling.
To glare down at someone means to stare at a person in a fierce or angry way.
Gulp down in this context can be used to connote the following:
Therefore, the connotation of the words from the passage means that when Jonny got to Buck Merril's door, Jonny became scared and tried to repress his reaction to Buck's angry looks.
Learn more in the link below:
https://brainly.com/question/13135002