Barrel is related to Gun. Gun can be used for Fire. Fire is related to Warmth. Warmth is related to Summer. 
Pass is related to Bottom. Bottom is related to Direction. 
Barrel <--RelatedTo--> Gun --UsedFor--> Fire <--RelatedTo--> Warmth <--RelatedTo--> Summer 
Pass <--RelatedTo--> Bottom <--RelatedTo--> Direction 