Shelley creates an atmosphere of horror using language by using various devices as well as by decribing how Frankenstein was feeling. Shelley starts off by mentioning that it was a "dreary night of November". November is a winter month, a season usually associated with death and gloom(i.e trees dying, animals hybernating). That by itself forshadows that the story that follows is going to be filled with gloom and possibly death, which fills the reader with dread. Shelley uses pathethic fallacy to accentuate the gloomy atmosphere ( "rain pattered dismally" ). This gives an inanimate object (rain) a human feeling (dismal), making it seem as if it was so gloomy, even rain, a thing with no emotion or feelings was "dismal". This is especially effective as it highlights the overall mood and atmospere of the scene, allowing readers to feel and imagine what it must feel like to be in the protagonist's position.
The excerp is filled with negative words and ideas, such as "catastrophe", "wretch", "agony", "detain" and "convulsive". This creates a somber mood, which is later deepened by Shelley when she describes Frankenstein's disgust and horror towards his own creation (his main reason being that his creation was not attactive, showing how superficial and materialistic he is). By describing Frankenstein's doing as a "catastrophe", readers are put under the impression that the creature is monstrous and repulsive, though later, readers might feel slightly angered towards Frankenstein as they realize that the creature was innocent, and that it was Frankenstein who was at fault, for creating him which such enthusiasm and later rejecting and abandoning him. He says he feels "detained" when the creature reached out towards him, telling us that he feels trapped, like he cannot escape from his doings.
The main linguistic device used is descriptive and emotive language. Shelley describes the scene and mood in great detail, in a way that would pull the reader's emotions. A good example would be Shelley describing the creature; "Beautiful! -- Great God! His yellow skin scarcely covered the work of muscles and arteries beneath; his hair was of a lustrous black, and flowing; his teeth of pearly whitenessl but these luxuriances only formed a more horrid contrast with his watery eyes, that seemed almost of the same colour as the dun white sockets in which they were set, his shrivelled complexion and straight black lips." The creature is first described as being quite attractive, but Shelley made all the good features seem negative ("formed a more horrid contrast") and finally ending it by describing the creature's negative features. Her description was so vivid, readers could clearly picture the creation in their minds.
Mary Shelley cleverly combines this with emotive language, expressing the protagonist's reaction and feelings towards the creature ("How can I describe my emotions at this catastrophe, or how delinete the wretch whom with such infinite pains and care I had endeavoured to form?"). Another good example would be the fourth paragraph, describing Frankenstein's reaction to his creation. It was both descriptive and heart-wrenching as readers probably sympathized with the creation, for he did nothing wrong and yet was rejected by his creator. This adds to the atmosphere as the dread is slowly being replaced by fear and sympathy.
A further example of emotive language would be how (in paragraph 3) Frankenstein is trying to remind himself why and how he allowed himself toobsess over his experiment ("I had desired it with an ardour that far exceeded moderation; but now I had finished, the beauty of the dream vanished, and breathless horror and disgust filled my heart"). Filled with emotion, Shelley describes how Frankenstein let the experiment bring out the worst in him and at the end, he wasn't happy with his result. Disappointment and regret rings through every word and readers are able to comprehend why Frankenstein was so horrified in the first place. Shelley even made Frankenstein's feelings obvious from his actions ("traversing in my[Frankenstein's] bedchamber"). Traversing is something someone does when disturbed, and it is made clear that Frankenstein is disturbed about his creation and how he regrets making it.
Shelley uses a lot of contrast. The most obvious example would be the contrast between life and death ("I collected the instruments of life around me, that I might infuse a spark of being into the lifeless thing that lay at my feet."). This probably best emphasizes on the atmosphere that surrounds Frankenstein as he struggles to decide what he feels towards the creature. Shelley described Frankenstein's experiment's main purpose to be "infusing life into an inanimate body". Here, Shelley makes use od contrast to accent the fact that the creature was inanimate (not meant to be alive) and Frankenstein, who succeeded despite trying to do something deemed impossible, might not have done the right thing.
Also, Shelley uses alot of contrast between light and darkness ("candle nearly burnt out", "half extinguished light", "dull" [ all words from the semantic field of light]), possibly to symbolise how things are going to get darker in the story (light is going to burn out [good events are going to turn bad]), creating a feeling of suspense as well as fear.
Shelley refers to another great piece of literature (Dante's Inferno) as well as its writer. In Inferno, Dante visits Hell and sees all kinds of monsters and evil creatures, things more horrible than anyone has ever imagined. By saying that Frankenstein was "a thing such as even Dante could not have conceived", Shelley makes the reader question their views on the monster. Is it really as bad as Frankenstein makes it seem? It also might insinuate that Frankenstein is saying that maybe creating this creature was a sin, as Dante also descirbed all the horrible sins he witnessed in Hell in Inferno. By making this connection, Shelley makes it easier for the reader to try and imagine the horrors Frankenstein was facing, as the horrors in Inferno was said to be the worst kind of horrors any man could witness.
Since this book was written in the 1800's, readers reacted to this book very extremely. The idea of bringing something made of dead body parts to life was unthinkable, and defied everything they stood for and believed in. They would be appalled, and all this contributed to the haunted, dismal atmosphere Shelley is creating. Readers at that time were not used to be scared by horror stories, and so this reaction was completely new to them, making it very extreme.
Overall, Shelley makes effective use of language to create atmosphere. Her descriptions make it easier for the reader to imagine the scene and try to understand the feelings that are being felt by Frankenstein.
