How is the element of suspense built in "The Signal-Man" by Charles Dickens and "How It Happened" by Sir Arthur Conan Doyle?

Dickens starts building
suspense in "The Signal-Man" by using imagery. repetition and punctuation. An example of
Dickens distinctive imagery is the description of the signal-man as being distorted:
"his figure was foreshortened and shadowed." "Foreshortened” is a term in art that means
to make certain parts shorter than in real life to create the correct allusion of
distance and angle to give the correct perspective. The narrator leaves the reader with
a very vivid image of the signal-man looking somehow wrong compared to how he should
look--he is somehow distorted. This builds suspense because it prompts questions in the
reader's mind about how and why and in what way.

Dickens also repeats
significant words to build a certain sensation and, with the sensation, a feeling of
suspense. For instance, in the first twelve paragraphs, "down is repeated twelve times:
 "down the Line"; "down in the deep"; "down and speak"; "down at him"; "down to him";
etc. He also uses punctuation to build suspense by creating a cadence that inspires a
feeling of tension and suspense, like in the following passage where punctuation and the
repetition of "and" create a feeling of reluctance and hesitance in the first-person
narrator and in the reader:

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I resumed my downward way, and stepping out upon
the level of the railroad, and drawing nearer to him, saw that he was a dark sallow man,
with a dark beard and rather heavy
eyebrows.

Doyle
and Dickens both start their stories in medias
res, in the middle, so we are without knowledge of circumstances or
characters at the out set of the story. He uses distinctive imagery, as Dickens does,
along with another technique. At the start of "How It Happened," Doyle builds a
compelling image through the narrator's description of his experience--a description
inexplicably coming to us through "She": "She was a writing medium. This is what she
wrote." This opening both builds suspense for all the unexplained things it suggests
(e.g., who is she, what is a writing medium) and foreshadows what will come thus adding
to the suspense. The narrator, framed by the "writing medium," imparts a distinctive
image when he says that some parts of his memory are "most distinct" and some vague,
"like some vague, broken dreams," making it hard to tell his whole story: "That is what
makes it so difficult to tell a connected story."

Doyle also uses
another technique when he starts focusing upon physical events--rather than upon
impressions and psychological experiences--that happen as they occur in chronological
order and through the experience of the first-person narrator. For example, Doyle puts
emphasis upon the brakes giving out; being unable to throw the car into reverse; Perkins
placing his hands upon the wheel; the wheels of the car being on the bank; and other
such physical details. The result is a build up of suspense as one physical event after
another impacts the narrator and Perkins--and the reader at the same time. The narrator
starts with "the big motor, with it's glaring headlights and glitter of polished brass,
[ominously] waiting for me outside," then moves to "I clapped on both brakes, and one
after the the other they gave way," and ends with "I whirled round my wheel with all the
strength of my wrists. ... my right front wheel struck full on the right-hand pillar,"
with many, many more suspenseful physical events in between.