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Here we present some examples:

• If anything can go wrong, it will.
• It is impossible to make anything foolproof because fools are so ingenious.
• An experiment may be considered succesful if no more than 50 % of the data obtained must be discarded to get a result which satisfies the theory to be proved.
• No experiment is a complete failure. It can always serve as a bad example.
• When all else fails, read the directions.
• Specified environmental conditions will always be exceeded.
• Any error that can creep in, will. It will be in the direction that will do the most damage.
• All constants are variable.
• In a complex calculation, one factor from the numerator will always move into the denominator.
• In any given computation, the figure that is most obviously correct will be the source of error.
• In any given miscalculation, the fault will never be placed if more than one person is involved.
• Dimensions will always be expressed in the least usable terms.
• Interchangeable parts won't be.
• Any wire or tube cut to length will be too short.
• Identical units tested under identical conditions will not be identical in the field.
• Availability of a part is inversely proportional to the need for the part.
• The easiest way to find something you lost is to buy a replacement.
• Don't force it. Get a bigger hammer.
• If you don't understand a particular word in a technical article, ignore it. The text usually makes perfect sence without it. (With the exception of Maskinelement books, of course.)
• Make three consecutive correct guesses and you will establish yourself as an expert.
• A man who can smile when things go wrong has thought of someone he can blame it on.
• A dropped tool will land where it can do the most damage. (Also known as the law of selective gravitation.)
• The accessibility of a part which falls from the workbench varies directly with the size of the part and inversely with the importance of the part in completing the job.
• Tolerance will accumulate unidirectionally toward maximum difficulty of assembly.
• Hermetic seals will leak.
• After an instrument has been fully assembled, extra components will be found on the bench.
• After the last 16 mounting screws are removed from an access plate, it will be discovered that the wrong access plate has been removed.
• Any safety factor set as a result of practical experience will always be exceeded.
• Components that must not and cannot be assembled improperly will be.
• The probability of a dimension being omitted from a drawing is directly proportional to its importance.
• The most logical way to assemble components will be the wrong way.
• The more innocuous a design change appears, the further its influence will extend.
• The necessity for making a major design change increases as the job nears completion.
• A part will be made exactly as specified in a drawing only when the drawing has an error.
• After all, there is a Murphy in every crowd.
• No job is so simple that it can't get screwed up.